ChatGPT answers, unedited

If by agency-friendly billing you mean one agency account pays the underlying costs, while clients can be charged centrally for SMS, email sends/credits, and your own services, there are a few distinct models.

The strongest fit: HighLevel

HighLevel is unusually purpose-built around this model. Its agency plans support client sub-accounts, an agency-level wallet, usage-based rebilling, markups, and SaaS subscriptions. Its current documentation specifically covers rebilling SMS/phone, email, AI, and other usage-based services. HighLevel Support Portal HighLevel Support Portal

You can essentially structure it as:

Client → pays your agency → agency pays HighLevel/communication provider → usage is attributed to the client

For example, you could charge:

• $199/month platform/service fee
• $0.XX per SMS
• $X per 1,000 email sends
• $XX for additional services
• Your desired markup on usage

HighLevel's SaaS Wallet can also charge a client's card for prepaid credits, with credits deducted as messages/emails/calls are consumed. HighLevel Support Portal

Its current pricing page says the $497/month Agency Pro plan includes SaaS Mode, which is specifically designed to sell subscriptions and automatically rebill SMS, email usage and other features. GoHighLevel

gohighlevel.com
help.gohighlevel.com

Other platforms

The important distinction is that Vendasta is more oriented toward an agency building a catalog/marketplace of third-party services, whereas HighLevel is more naturally suited to an agency operating the marketing infrastructure itself and charging clients for consumption. CRM Reviews Stack Space Solutions

If you're building an agency billing stack

I'd separate the requirements into three layers:

1. Recurring services

• $500/mo marketing management
• $99/mo website hosting
• $299/mo SEO
• etc.

2. Consumption

• SMS credits
• Email sends
• Voice minutes
• AI usage
• WhatsApp messages

3. One-off services

• Campaign setup
• Landing-page build
• Creative production
• Consulting
• Migration/setup fees

HighLevel can handle the first two particularly well, and its newer Marketplace usage-based pricing can also support per-execution, per-message, and custom usage charges. HighLevel Support Portal

So if your goal is essentially "Stripe + client accounts + CRM + SMS/email infrastructure + metered usage + agency markup in one system," HighLevel is probably the first platform I'd investigate.

One caveat: the exact billing mechanics differ by communication provider and plan. For example, HighLevel's current documentation distinguishes LeadConnector/LC Email from providers such as Mailgun, and some rebilling functionality is plan-dependent. HighLevel Support Portal

If you tell me how you want to charge clients (e.g. prepaid SMS credits vs. monthly invoice, your desired markup, and whether you're already using Twilio/SendGrid/Mailgun), I can map out 3–5 concrete stacks and show exactly how the money flows from client → agency → provider.

If by “agency-friendly billing” you mean one agency account pays for the underlying usage, while each client can be charged centrally for email sends, SMS usage/credits, and recurring or one-off services, there are a few categories worth considering.

Strong fit: gohighlevel.com

HighLevel is particularly designed around this agency/reseller model.

• Central agency wallet: your agency funds usage centrally, including phone/SMS, email, AI, email validation, and other usage-based services. HighLevel Support Portal HighLevel Support Portal
• Client rebilling: supported usage can be automatically passed through to individual client sub-accounts.
• Markup: on the $497/month Agency Pro plan, you can rebill supported phone and email usage with an agency markup, rather than merely passing through your cost. GoHighLevel HighLevel Support Portal
• SMS: its native phone system handles SMS/MMS, with usage-based billing and rebilling. HighLevel Support Portal
• Email: email usage can likewise be rebilled to sub-accounts. HighLevel Support Portal
• Services: HighLevel also has a reselling system for things such as listings, domains, WhatsApp, WordPress hosting, SEO-related services, and other add-ons, where you can establish a client-facing price. HighLevel Support Portal
• SaaS mode: Agency Pro adds automated sub-account creation and a SaaS configurator, making it possible to sell your own packaged offering under your agency brand. GoHighLevel

So you could conceptually have:

Client A → $299/mo platform + $X SMS + $Y email + $Z services
Client B → $499/mo platform + $X SMS + $Y email + $Z services

while your agency maintains the underlying wallet/vendor relationship.

Other platforms worth investigating

Vendasta is more oriented toward agencies that want to resell a catalog of third-party software/services to clients. That's potentially a better architectural fit if “services” is the important part—for example, selling reputation management, SEO, websites, advertising, etc.—rather than primarily operating the clients' CRM/marketing automation. Stack Space Solutions

There is also a distinction worth making:

The key thing I'd investigate for your use case is HighLevel's distinction between rebilling and reselling. Rebilling is specifically designed for consumption such as SMS/email, whereas reselling is designed for packaged services/subscriptions. HighLevel Support Portal

If you tell me what you're currently using for email/SMS (e.g. Twilio, Mailgun, SendGrid, Klaviyo, etc.) and what “services” you want to bill for, I can compare HighLevel vs Vendasta vs a Stripe-based setup vs building your own agency billing layer, including how each handles credits, markup, invoices, prepaid balances, and usage tracking.

If your goal is “one agency account pays for everything, then we centrally charge each client for their SMS/email usage + our services”, HighLevel is probably the closest fit.

Best options

1. HighLevel — strongest match

gohighlevel.com is specifically designed around the agency/reseller model.

Its Agency Wallet lets you centrally fund usage. Client sub-accounts consume that balance for things such as email, SMS/phone, AI and other usage-based services. You can then rebill the client, either at cost or with a markup depending on your plan. HighLevel Support Portal HighLevel Support Portal

For example:

Client A → 50,000 emails + 2,000 SMS → HighLevel tracks usage → your agency pays the underlying cost → Client A is automatically charged according to your pricing.

HighLevel also supports SaaS Mode, where you can sell subscriptions and automatically rebill clients for SMS, email and other usage. GoHighLevel

The particularly useful part for your use case is that you can combine usage billing + recurring services. So you could have:

• $499/month marketing service
• $50 SMS credit bundle
• $25,000 email credits
• $0.02/SMS overage
• Website hosting
• AI usage
• Automation/workflow charges
• One-off setup fees

all under the same client relationship.

HighLevel's current documentation also explicitly describes client wallets, auto-recharge, usage thresholds, rebilling and agency markups. HighLevel Support Portal

If you're an agency building a repeatable client-billing model, this would be my first platform to evaluate.

2. Vendasta — better if you're selling lots of different services

vendasta.com is worth looking at if your business is more of a multi-product agency/reseller than primarily a CRM/communications agency.

It has centralized client billing, recurring invoices, one-time charges, setup fees, product catalogs and white-labeled purchasing. Vendasta Vendasta

The distinction is that Vendasta is stronger as a “sell and bill a catalog of services/products” platform, whereas HighLevel is stronger when the actual underlying service is CRM + marketing automation + email/SMS + communications.

3. Twilio + Stripe — best if you're building your own system

If you have a technical team and want complete control, Twilio + Stripe is probably the most flexible architecture.

You'd maintain:

• Client accounts
• Usage ledger
• SMS credits
• Email credits
• Service subscriptions
• Markups
• Minimum balances
• Auto-recharge
• Invoices
• Stripe payment methods

Twilio handles the communication infrastructure while Stripe handles the money. But you'd have to build the agency billing layer yourself. That's a substantial difference from HighLevel.

My recommendation

If your requirements are specifically:

Agency pays centrally → clients consume SMS/email → usage gets tracked per client → clients automatically pay you → you add markup → you also charge monthly service fees

I'd rank them:

1. HighLevel — best out-of-the-box
2. Vendasta — best for a broad agency/reseller catalog
3. Twilio + Stripe — best if you're building a proprietary platform

One important caveat: HighLevel's exact rebilling capabilities depend on the plan and whether you're using its LC Email/LC Phone versus external Twilio/Mailgun, so I'd validate your desired pricing model against the current plan before committing. HighLevel's current documentation says markup-based rebilling is available on its Agency Pro/SaaS setup for supported services. HighLevel Support Portal HighLevel Support Portal

If you tell me what you're actually selling (e.g. email marketing, SMS, AI, websites, ads, CRM) and roughly how many clients, I can narrow this down to the best 2–3 platforms and show you how the billing flow would work.

If your goal is “one agency account pays the software wholesale cost, then we centrally charge each client for their email sends, SMS credits, and agency services”, there are a few strong options. The closest fit is HighLevel.

Best fits

1. HighLevel — probably the closest match

HighLevel has an Agency Wallet where your agency funds usage centrally. Email, phone/SMS and other usage can then be attributed to individual client sub-accounts. You can rebill clients, including applying a markup on supported services. HighLevel Support Portal HighLevel Support Portal

The current plans are:

• $297/mo Unlimited — unlimited sub-accounts and rebilling of phone/email usage without markup.
• $497/mo Agency Pro — adds SaaS Mode and allows phone/email rebilling with markup. GoHighLevel

The $497 plan is particularly interesting if you want something like:

Client pays us $499/month → includes 10,000 emails + 500 SMS → additional usage billed automatically → plus our managed services fee.

HighLevel's SaaS Mode is specifically designed around this model: you create plans, set pricing, include things such as usage credits, and automatically bill clients through Stripe. GoHighLevel

HighLevel also now explicitly supports email rebilling, with the agency able to apply a multiplier/markup to email costs. HighLevel Support Portal

gohighlevel.com

2. Vendasta — better if “services” are the bigger part

Vendasta is worth looking at if you're less interested in usage-based communications and more interested in creating a catalog of agency services.

For example:

• Website — $499 setup
• SEO — $799/mo
• Email marketing — $299/mo
• SMS — $X per 1,000
• Reputation management — $199/mo
• Google Ads management — $500/mo

Vendasta has wholesale and retail subscriptions, so you can see what you pay vs. what you charge the client, and it supports recurring billing, one-time invoices, custom line items, automatic payment collection, etc. Vendasta Support Vendasta

That's a particularly good fit if your agency wants a white-label marketplace + billing system, rather than primarily a marketing automation platform.

vendasta.com

My recommendation

If your requirement is specifically:

“Central agency account → clients underneath it → track their email/SMS consumption → automatically charge them → add our markup → also charge recurring/one-off agency service fees”

I'd start with HighLevel Agency Pro.

The architecture is basically:

Your Agency
→ Agency Wallet
→ Client A
→ Client B
→ Client C
→ Client D

And each client's billing can combine:

Base platform fee + SMS usage + email usage + other usage + your services/retainer

That is much closer to a reseller/SaaS billing model than what you'd get from a conventional email platform like Mailchimp or Klaviyo.

If, however, your agency uses lots of different third-party products and wants one branded client billing portal/catalog for all those services, I'd investigate Vendasta first.

If you tell me what you're currently using for email, SMS, CRM, and invoicing (e.g. Twilio + Mailgun + HubSpot + Stripe), I can also compare the best 3–5 setups for your exact agency billing model, including which ones let you mark up SMS/email usage automatically.

If you mean “one agency account pays for the underlying usage, then automatically bills each client for their SMS/email consumption plus our own services”, HighLevel is probably the strongest fit.

Best options

| Platform | SMS

If you want to centrally bill clients for email sends, SMS credits, and managed services, you’re looking for an agency/reseller platform with sub-accounts, usage tracking, credit wallets, and markup billing. The strongest options depend on whether you want a full marketing platform or mainly a billing layer.

Best agency-friendly options

My shortlist by use case

1. You want a “mini SaaS” agency model

Best fit: HighLevel

HighLevel is probably the closest match if you want:

• one agency account
• unlimited client sub-accounts
• clients billed under your brand
• SMS/email usage passed through with markup
• recurring SaaS fees plus usage fees

Its wallet/rebilling system is designed around charging clients for communication usage rather than the agency absorbing those costs. HighLevel Support Portal HighLevel Support Portal

Example offer:

• $299/month “marketing system”
• - $0.02/SMS sent
• - $5 per 10,000 emails
• - managed campaign fees

2. You mainly sell SMS campaigns

Best fit: SlickText reseller

SlickText supports agency resellers where you purchase message credits at reseller rates, package them into your own services, and set your client pricing. SlickText It also supports managing multiple client dashboards and credit usage. SlickText

Example:

• Client pays $500/month
• Includes 20,000 SMS credits
• Extra messages billed automatically

3. You already have your delivery tools and need billing

Best fit: ManyRequests + Stripe

ManyRequests is more of an agency operating/billing layer:

• subscriptions
• service catalogs
• invoices
• usage-based billing
• client portals

It works well if you want to sell packages like:

• “10 campaigns/month”
• “50,000 email sends”
• “SMS management”
• “AI automation hours”

ManyRequests### 4. You want a fully white-label communications product

Look at reseller-focused messaging platforms such as:

• GlobVoice — combines SMS, email, WhatsApp, voice, and agency resale workflows. GlobVoice
• SMSLocal — wholesale credits, markup controls, and consolidated reseller billing. SMSLocal

What I would choose

• Marketing agency selling automation + CRM + messaging: HighLevel
• SMS/email agency product with margins: HighLevel or SlickText
• Agency doing many custom services: ManyRequests + Stripe + your delivery stack
• Building your own branded SaaS: Twilio APIs + Stripe usage billing

A good agency billing stack usually has:

1. Client sub-accounts
2. Usage metering (emails sent, SMS used, minutes, AI credits)
3. Automatic credit top-ups
4. Markup controls
5. Client invoices/payment collection
6. Usage dashboards

If you tell me whether you’re selling CRM/marketing automation, email marketing, SMS campaigns, or AI/chat/voice services, I can narrow this to the best 2–3 platforms.

If by “agency-friendly billing” you mean one agency account pays the software wholesale cost, then you centrally rebill each client for email sends, SMS usage/credits, and your own services, there are a few strong options.

Best fits

1. gohighlevel.com — probably the closest match

HighLevel is unusually well suited to this model. It has:

• Agency Wallet — your agency funds usage centrally.
• Client/sub-account billing — usage can be charged back to individual clients.
• SMS/phone rebilling — clients can be billed for their actual messaging usage.
• Email rebilling — email usage can be passed through to clients.
• Markup — on the Agency Pro/SaaS setup, you can charge more than your wholesale cost.
• Resold services — domains, email validation, SEO, WordPress hosting, AI usage, etc. can also be resold.
• White-labeling — you can present the platform as your own service. HighLevel Support Portal HighLevel Support Portal

HighLevel explicitly describes the model as: agency pays the wholesale usage → client is billed for the usage → agency can add markup and retain the difference. HighLevel Support Portal

Its current pricing lists Agency Unlimited at $297/mo and Agency Pro at $497/mo, with SaaS Mode/rebilling capabilities on Pro. GoHighLevel

This would be my first choice if SMS + email sending are core parts of what you're selling.

2. vendasta.com — better for broader agency services

Vendasta takes a slightly different approach. It's particularly good if your business sells a bundle of services rather than primarily operating an email/SMS platform.

You can:

• Create a catalog of your services.
• Bundle third-party products with your own services.
• Charge one-time or recurring fees.
• Automatically invoice clients.
• Use Stripe Connect for payments.
• White-label the client purchasing/billing experience.
• Add setup fees, taxes, recurring charges, etc. Vendasta

So, for example, you could theoretically have a client subscription like:

Marketing Package — $799/mo
Email: 50,000 sends
SMS: 2,000 credits
Campaign management: $300
Reporting: $100
SEO: $199

Vendasta is stronger than HighLevel if your primary concern is selling and billing a portfolio of different agency services.

How I'd choose

My recommendation

If your desired architecture is:

Your agency → one master account → 50 clients → each client consumes email/SMS → automatically calculate their usage → bill them + your service fee + markup

I'd go with HighLevel first. Its wallet/rebilling system was specifically designed around this agency model. HighLevel Support Portal HighLevel Support Portal

If instead you want:

Your agency → product/service catalog → clients buy packages → recurring invoices → bundle SEO, ads, websites, reputation management, email, SMS, etc.

I'd look harder at Vendasta.

One important distinction: neither is simply a generic “usage billing engine.” If you're building your own SaaS and want to aggregate usage from your own email provider + Twilio + other vendors and produce a single client invoice, I'd look at a different category of software (e.g. Stripe-based usage billing / metering platforms).

If you want to centrally bill clients for email sends, SMS credits, usage, and services, you’ll want something with agency/reseller billing, not just a marketing platform. The best fit depends on whether you want to resell a platform, meter usage, or simply invoice clients.

Best agency-friendly options

My shortlist by scenario

1. You want to sell "marketing software" under your agency brand

Choose HighLevel.

Typical setup:

• Client pays you $297–$997/month
• You create a client sub-account
• You bundle: - CRM
• Email campaigns
• SMS messaging
• Automations
• Reputation tools
• You add markup on usage

This is probably the closest match to a "mini HubSpot/Salesforce for agencies" model. GHL Experts HighLevel Support Portal

2. You mainly need SMS credit billing

Choose SlickText reseller.

Example:

• Your cost: wholesale SMS credits
• Client package: "10,000 SMS/month"
• Overages: your chosen rate
• One agency account manages multiple brands

SlickText specifically supports agencies that want to own the billing relationship rather than having clients billed directly. SlickText

3. You already have email/SMS providers and just need billing infrastructure

Use an agency billing layer:

• ManyRequests
• Stripe Billing
• Chargebee
• Recurly
• Orb (for usage-based billing)

A common architecture:

Email provider (SendGrid/Mailgun/etc.)
          +
SMS provider (Twilio/etc.)
          +
Usage tracking database
          +
Stripe Billing
          +
Client portal/invoices

This gives you full control over:

• per-email pricing
• per-SMS pricing
• credits
• bundles
• retainers
• overage charges

4. You want a true reseller SaaS model

Look at platforms built around:

• subaccounts
• white-label login
• client plans
• usage limits
• markup rules

HighLevel and Chirply are closer to this model. GHL Experts Chirply

Features I’d prioritize

For your use case, I’d require:

✅ Client-level usage tracking
✅ Prepaid credits or monthly allowances
✅ Automatic overage billing
✅ Separate client workspaces
✅ White-label portal
✅ Stripe integration
✅ API/webhooks for usage
✅ Ability to set your own markup
✅ Exportable billing reports

A setup I often see agencies use:

• HighLevel → client-facing marketing platform
• Stripe Billing → payments
• Twilio/Mailgun/SendGrid → raw communication costs
• Custom usage dashboard → margin tracking

If you tell me whether you’re trying to bill for (a) your own agency services + messaging, (b) resell a SaaS platform, or (c) build a white-label marketing product, I can narrow this to the best 2–3 options.

For your use case, I’d require:

✅ Client-level usage tracking
✅ Prepaid credits or monthly allowances
✅ Automatic overage billing
✅ Separate client workspaces
✅ White-label portal
✅ Stripe integration
✅ API/webhooks for usage
✅ Ability to set your own markup
✅ Exportable billing reports

A setup I often see agencies use:

• HighLevel → client-facing marketing platform
• Stripe Billing → payments
• Twilio/Mailgun/SendGrid → raw communication costs
• Custom usage dashboard → margin tracking

If you tell me whether you’re trying to bill for (a) your own agency services + messaging, (b) resell a SaaS platform, or (c) build a white-label marketing product, I can narrow this to the best 2–3 options.

Yes. If your goal is one agency account that can centrally pay for usage and then charge individual clients for email sends, SMS credits, and your own services, the strongest options are:

1. HighLevel — probably the closest match

gohighlevel.com

HighLevel is particularly well suited if SMS + email + agency client accounts are central to your business.

Its current billing model has an Agency Wallet that pays for usage-based services. Phone/SMS/email usage can then be rebilled to individual client sub-accounts, with the agency adding a markup. HighLevel Support Portal HighLevel Support Portal

For example:

• Your agency buys $100 of SMS usage.
• Client A consumes $18.
• Client B consumes $42.
• HighLevel tracks usage by sub-account.
• You can rebill those clients, potentially with your own markup.
• You can also sell fixed-price SaaS subscriptions and services alongside usage. HighLevel Support Portal

HighLevel also explicitly supports phone/SMS/email usage and automatic wallet replenishment. HighLevel Support Portal

Best if: you want the billing tightly integrated with your CRM/automation platform rather than building a billing layer yourself.

2. Vendasta — best if you're selling lots of different services

vendasta.com

Vendasta is arguably stronger than HighLevel for the "agency as a reseller/service provider" model.

It has a wholesale → retail model where you pay the wholesale cost and establish the retail price your client pays. Each product creates a wholesale subscription for you and a retail subscription for the client. Vendasta Support Vendasta Support

You can also:

• Create recurring client subscriptions
• Add one-time/custom charges
• Bundle products and services
• Generate consolidated invoices
• Collect payments automatically
• Add your own products and services
• White-label the client-facing experience Vendasta Vendasta

So you could theoretically have an invoice like:

Marketing Platform — $299/mo
Email — 50,000 sends — $75
SMS — 2,000 credits — $60
SEO management — $500
Creative services — $300
Total — $1,234

Best if: your agency sells a portfolio of software + usage + managed services, rather than primarily being a CRM/marketing-automation reseller.

3. Twilio — best communications infrastructure, but less turnkey

twilio.com

Twilio is excellent if you're building your own system.

You can create subaccounts for individual clients, and Twilio bills their usage back to your main account. It also provides consolidated billing groups and programmatic usage data. Twilio Twilio

The catch: Twilio doesn't give you the complete agency billing experience that HighLevel/Vendasta does. You'd generally build the client-facing markup, invoices, service catalog, credit packages, etc. yourself—often using Stripe.

My recommendation

If your requirement is specifically:

"I want my agency to centrally pay for email/SMS usage, allocate consumption to clients, add markup, and bill clients for that plus our other services."

I'd shortlist them like this:

1. HighLevel — best all-in-one for SMS + email + automation + client usage rebilling
2. Vendasta — best for multi-service agency/reseller billing and white-label commerce
3. Twilio + Stripe — best if you want maximum control and are willing to build the billing layer

The key distinction is that HighLevel is more usage/rebilling-native, whereas Vendasta is more product/catalog/subscription/invoice-native. HighLevel's documentation explicitly describes rebilling as charging clients for usage plus an agency markup. HighLevel Support Portal

If you tell me whether you're primarily selling email marketing, SMS, SaaS/CRM, or managed services, I can narrow this down to the 2–3 platforms that actually fit your billing model and compare their current pricing/markup mechanics.

twilio.com

Twilio is excellent if you're building your own system.

You can create subaccounts for individual clients, and Twilio bills their usage back to your main account. It also provides consolidated billing groups and programmatic usage data. twilio.com twilio.com

The catch: Twilio doesn't give you the complete agency billing experience that HighLevel/Vendasta does. You'd generally build the client-facing markup, invoices, service catalog, credit packages, etc. yourself—often using Stripe.

My recommendation

If your requirement is specifically:

"I want my agency to centrally pay for email/SMS usage, allocate consumption to clients, add markup, and bill clients for that plus our other services."

Vendasta is more oriented around agencies packaging and reselling multiple third-party services—SEO, reputation, listings, websites, advertising, etc.—rather than purely usage-based messaging. It can make sense if your business model is essentially a digital-services marketplace under your agency brand.

4. Simvoly — good white-label SaaS model

Simvoly is interesting if you're building a branded client platform. Its agency offering supports white-labeling and lets agencies create their own subscription plans/add-ons and resell websites, funnels, marketing automation, SMS/WhatsApp/voice, etc.

Yes. If your goal is one agency account that pays wholesale costs, then bills each client for email sends, SMS/phone usage, credits, and your own services, there are a few strong options—but HighLevel is probably the closest fit.

Best fits

1. HighLevel — probably the closest match

gohighlevel.com

HighLevel is unusually well suited to this model. Its Agency Wallet pays for usage-based services, while supported costs can be rebilled to individual sub-accounts. You can pass costs through at cost or add a markup. HighLevel Support Portal HighLevel Support Portal

It currently supports rebilling around things such as:

• SMS/phone usage
• Email sends
• AI usage
• Workflow/premium usage
• Domains
• Various other resold services

For example, HighLevel's current documentation says LC Email usage can be rebilled, with markup available on its $497/month Agency Pro plan; phone/SMS usage similarly supports agency rebilling. HighLevel Support Portal

The interesting part for your use case is that you can combine usage billing + SaaS subscriptions + your own services. HighLevel's SaaS Mode lets you configure client plans, pricing, trials, included credits, and Twilio/communications rebilling. GoHighLevel

So you could theoretically structure something like:

Client A — $499/month
CRM/software: $299
Email: $25
SMS: $75
Reputation management: $50
Managed services: $50

…and have the communication consumption calculated/rebilled rather than manually invoicing every month.

HighLevel also has usage-based billing for Marketplace apps, including per-message and custom usage charges, with agency markups and usage limits. HighLevel Support Portal

My pick if communications usage is central to your business.

2. Vendasta — better if you're building an agency product catalog

vendasta.com

Vendasta is particularly strong if your model is:

"We sell clients a bundle of software + marketing + advertising + managed services."

It has wholesale and retail subscriptions, meaning Vendasta tracks what you pay versus what your client pays. Vendasta Support

It also lets you create your own products/services, bundle them with marketplace products, and invoice clients for essentially anything you sell. Vendasta Vendasta

The distinction I'd make is:

• HighLevel: better for metered communications consumption (SMS/email/phone) + CRM automation.
• Vendasta: better for agency commerce/catalog management—lots of products, subscriptions, services and packages.

Vendasta's billing platform supports recurring charges, one-time charges, setup fees, taxes, invoices and payments in one system. Vendasta

What I'd choose

If you specifically mean:

"I want to buy SMS/email capacity centrally, let 50–500 clients consume it, automatically charge each client for what they used, add my markup, and also put my recurring agency services on the same bill."

I'd start with HighLevel.

If you instead mean:

"I want an agency commerce platform where I can sell 20 different SaaS products, advertising, SEO, websites, managed services, etc., and consolidate everything into client subscriptions/invoices."

I'd look harder at Vendasta.

The important thing is that HighLevel actually handles the metered SMS/email piece natively, rather than requiring you to build a usage-metering and invoicing layer yourself. HighLevel Support Portal HighLevel Support Portal

If you tell me roughly how you want to charge clients (e.g. "$X per 1,000 emails + $Y per SMS + $299/month management"), I can compare HighLevel vs Vendasta vs a Stripe-based setup specifically for that billing model.

If you mean agency software where you pay the underlying communication costs centrally, then automatically charge each client for their email sends, SMS usage/credits, and your own services, there are a few strong options.

Best fits

1. HighLevel — strongest match

This is probably the closest match to what you're describing.

• Agency Wallet: your agency centrally funds usage-based services.
• Client wallets: clients can have their own prepaid balances/auto-recharge.
• Rebilling: HighLevel can automatically charge a sub-account for its actual email, phone/SMS, AI and other usage.
• Markup: on supported plans, you can add your own markup and keep the margin.
• SaaS mode: lets you package the platform and services into your own client-facing plans.
• Central agency view: you can see usage and charges broken down by sub-account. HighLevel Support Portal HighLevel Support Portal HighLevel Support Portal

HighLevel's current V2 billing system is particularly relevant: it supports rebilling all usage-based products through the client/sub-account wallet, including Phone, Email, AI-related usage and other services. HighLevel Support Portal HighLevel Support Portal

For example, you could structure:

Client pays $299/month

• $0.XX per SMS
• $X per 1,000 emails
• $X for additional services

Your agency controls the pricing and collects the money; HighLevel handles the underlying usage accounting.

Its wallet system can also automatically recharge when the balance reaches a threshold. HighLevel Support Portal

gohighlevel.com

2. Vendasta — strongest for broader agency reselling

Vendasta is better if you're thinking beyond communications and want an agency marketplace + client billing platform.

It lets agencies:

• Create packages of products/services.
• Charge recurring monthly fees.
• Add one-time/custom charges.
• Generate invoices.
• Collect payments.
• Resell third-party services under the agency relationship.
• White-label the client experience. Vendasta Vendasta Support

Vendasta also has email/SMS campaigns, with email sending included in plans and SMS available as an add-on. Vendasta Documentation

vendasta.com

3. Mailgun — good infrastructure, weaker agency billing

Mailgun has subaccounts, so you can separate clients/domains and track usage at the subaccount level. However, Mailgun explicitly says that subaccounts cannot currently be billed separately; their usage rolls up to the primary account. Mailgun Documentation

So it's useful as the email infrastructure underneath your own billing system, but not the best answer if you want the platform itself to automatically charge clients.

mailgun.com

My recommendation

If your model is essentially:

Agency → 50 clients → agency pays communication provider → clients consume SMS/email → clients get automatically charged → agency adds markup → agency also bills for monthly services

I'd start with HighLevel.

It's unusually close to having a mini usage-based billing system built specifically for agencies. The combination of agency wallet + client wallets + usage tracking + rebilling + markup + SaaS plans is the key differentiator. HighLevel Support Portal HighLevel Support Portal

One important distinction: Vendasta is more compelling if the primary problem is reselling lots of different agency services, whereas HighLevel is more compelling if SMS/email/communications usage is a major part of the client bill.

If you tell me whether you're looking for email marketing, SMS, or both, and roughly how many clients/accounts you manage, I can narrow this down to the best 3 platforms and compare their markup, wallet, usage billing, Stripe, white-label, and API capabilities.

If your goal is “one agency account pays the wholesale usage, then we centrally bill each client for their email sends, SMS usage/credits, and additional services”, the strongest fit I’d look at first is HighLevel.

Best options

1. HighLevel — probably the closest match

gohighlevel.com is unusually well suited to this model.

It has an Agency Wallet where your agency funds usage centrally, while supported usage can then be rebilled to individual client sub-accounts. This covers things such as:

• Email usage
• SMS/MMS and phone usage
• WhatsApp usage
• AI usage
• Email validation
• Various other platform services

The important distinction is that HighLevel can do actual usage-based rebilling, rather than simply giving you a monthly invoice and leaving you to calculate each client's consumption manually. HighLevel Support Portal HighLevel Support Portal

On the current plans, Unlimited ($297/mo) supports phone/email rebilling without markup, while Agency Pro ($497/mo) adds rebilling with your own markup and SaaS Mode. GoHighLevel

For example:

Client A → 25,000 emails + 2,000 SMS → HighLevel calculates usage → client is charged according to your configured pricing.

You can also sell fixed-price services alongside usage. HighLevel's current reselling system includes things such as SEO, listings, domains, dedicated IPs, WhatsApp, WordPress hosting, workflow features, etc. HighLevel Support Portal

One particularly useful feature is that your agency receives the platform's usage invoice while your clients can receive invoices under your agency/Stripe setup. HighLevel Support Portal

2. Vendasta — better if you're primarily reselling services

vendasta.com is worth considering if your business model is more:

“We sell clients a bundle of digital marketing services.”

rather than:

“We operate their email/SMS/CRM infrastructure.”

Vendasta is particularly strong around packaging and reselling third-party services through an agency marketplace. HighLevel is generally the more natural fit if SMS + email consumption itself is a major billable component.

3. Stripe + your own infrastructure — most flexible

If you're building your own SaaS/agency platform, you could use Stripe as the billing layer and meter:

• emails sent
• SMS segments
• phone minutes
• AI credits
• storage
• API usage
• fixed monthly services

This gives you complete control over pricing and margins, but you'd have to build the metering, client wallets, invoices, usage reporting, payment collection, etc. yourself.

My recommendation

If you're specifically trying to create an agency “master account → client accounts → usage credits → automatic client billing” model, I'd rank them:

1. HighLevel — best turnkey solution
2. Vendasta — best for broad service reselling
3. Stripe + custom stack — best if you're building your own platform

And I'd lean HighLevel Agency Pro if you want to mark up SMS/email usage and make margin on the credits, rather than merely pass your costs through. HighLevel explicitly supports markup-based rebilling on Pro. HighLevel Support Portal HighLevel Support Portal

If you tell me what you're currently using for email/SMS (e.g. Mailgun, Twilio, SendGrid, Klaviyo, etc.) and whether clients need to see/use their own dashboard, I can narrow this down to 3–5 platforms that specifically support your desired billing flow.

rather than:

“We operate their email/SMS/CRM infrastructure.”

Vendasta is particularly strong around packaging and reselling third-party services through an agency marketplace. HighLevel is generally the more natural fit if SMS + email consumption itself is a major billable component.

3. Stripe + your own infrastructure — most flexible

If your goal is “one agency account pays the platform, but we can centrally charge each client for their email sends, SMS usage/credits, and our own services”, there are a few strong options—but HighLevel is probably the closest match.

1. HighLevel — strongest match

HighLevel has an Agency Wallet where your agency funds usage, while supported services used by individual sub-accounts can be rebilled to those clients. This specifically covers email and SMS/phone usage, among other usage-based services. HighLevel Support Portal HighLevel Support Portal

The particularly useful part is that on the higher agency tier you can add your own markup rather than merely passing through your cost. HighLevel's current documentation says:

• $297/month: unlimited sub-accounts and rebilling without markup for supported services.
• $497/month Agency Pro: SaaS Mode plus email/phone/text rebilling with markup. HighLevel Support Portal
• SaaS Mode lets you sell subscriptions to clients and automatically rebill things such as SMS and email usage. GoHighLevel

So you could theoretically structure a client as:

Marketing Platform — $299/mo
Email — $X per 1,000 sends
SMS — $X per message
AI usage — $X
Website/hosting — $X
Managed services — $X
Total — automatically charged to client

And your agency gets charged for the underlying usage while HighLevel handles the client-level rebilling.

gohighlevel.com
help.gohighlevel.com

2. Vendasta — better if you're selling a catalog of services

Vendasta takes a slightly different approach.

It's built around the concept of an agency having wholesale costs and retail/client pricing. When you activate a product for a client, Vendasta creates a wholesale subscription for your agency and a retail subscription representing what you charge the client. Vendasta Support

It also supports:

• Recurring client subscriptions
• One-time charges
• Custom products/services
• Bundling products
• Client invoices
• Automatic payment collection
• White-label client portal
• Marketplace products
• Email/SMS marketing products Vendasta Vendasta Documentation

That makes Vendasta particularly interesting if your agency sells something like:

Client A

• Website — $199/mo
• SEO — $499/mo
• Email marketing — $99/mo
• 25,000 email credits — $X
• 500 SMS credits — $X
• Managed Google Ads — $750/mo

You can treat those as products/services in your agency catalog and bill them centrally. Vendasta Vendasta Support

vendasta.com
vendasta.com

My recommendation

If usage-based billing is the key requirement, I'd rank them:

1. HighLevel → best for SMS/email usage + client rebilling + markup + SaaS subscriptions

2. Vendasta → best for selling lots of different products/services with centralized agency billing

The distinction is important: HighLevel is much more compelling if the thing you're primarily reselling is the marketing/CRM platform itself and its underlying communications usage. Vendasta becomes more compelling if you're essentially building an agency marketplace/catalog where email, SMS, SEO, websites, ads, reputation management, etc. are all separate billable products.

If you tell me what you're currently using for email/SMS (e.g. Mailgun, Twilio, SendGrid, HighLevel, Klaviyo, etc.) and roughly how you want to charge clients, I can narrow this down to the 3–5 best platforms and show exactly how each handles credits, markup, invoices, and client-level usage.

If your goal is “we pay the platform centrally, then charge each client for email sends, SMS credits, and other services—ideally with markup”, there are a few good options, but HighLevel is probably the closest fit.

Best options

1. HighLevel — probably your best match

HighLevel has an Agency Wallet + client rebilling model specifically designed for this.

Your agency can fund the wallet centrally. Client usage then gets attributed to the appropriate sub-account, and you can rebill the client. HighLevel currently supports rebilling for things such as SMS/phone usage, email usage, AI usage and other usage-based services. You can also apply a markup on supported services. HighLevel Support Portal HighLevel Support Portal

For example:

Client A → 25,000 emails + 1,000 SMS
Client B → 50,000 emails + 2,500 SMS
Client C → 500 SMS + SEO service

You can have HighLevel track those separately and charge each client's account rather than trying to reconcile everything manually.

The particularly useful part is that HighLevel distinguishes rebilling from reselling: usage-based things such as SMS/email can be rebilled based on consumption, while services such as listings, WhatsApp, branded apps, etc. can be sold as fixed-price services. HighLevel Support Portal

HighLevel's current documentation says rebilling with markup is available on the $497/month Agency Pro plan, while the $297 plan supports certain rebilling without markup. HighLevel Support Portal

gohighlevel.com

2. Vendasta — better if you're essentially a service reseller

Vendasta is worth looking at if your agency wants to sell lots of different services/products to clients rather than primarily operating a CRM/marketing platform.

Its model is more like:

Your agency → branded marketplace → client buys services → you collect the money → vendor/service costs are handled underneath.

That's particularly attractive if you're selling SEO, reputation management, listings, websites, advertising, etc. rather than just SMS/email. CRM Reviews

vendasta.com

3. SlickText — interesting if SMS is the main thing

SlickText has a genuine reseller model where the agency owns the billing relationship, purchases message credits at reseller rates, packages SMS into its services, and sets its own client pricing. SlickText

So if your model is primarily:

“We sell SMS credits to clients at $X per 1,000 messages”

SlickText is worth considering.

slicktext.com

My recommendation

If you're trying to build something like:

Agency
→ manages 20–100 clients
→ one master billing relationship
→ client pays you monthly
→ client gets charged for SMS + email sends + phone usage + AI credits + SaaS + services
→ you control the markup
→ ideally white-labeled

I'd start with HighLevel.

Its wallet/rebilling architecture is unusually close to exactly what you're describing. HighLevel explicitly describes the agency paying the underlying usage cost through its Agency Wallet and then charging the sub-account for the usage it generated. HighLevel Support Portal

If, however, you already have your own CRM/messaging stack and you're looking for a billing layer that sits on top of multiple vendors, that's a different problem—and I'd look at a combination of Stripe Connect + a usage-metering/billing platform rather than replacing your whole stack with HighLevel.

If you tell me what software you're currently using for email/SMS (e.g. Twilio, SendGrid, Mailgun, Klaviyo, HubSpot, etc.), I can narrow this down to the 3 best platforms for your exact agency billing model, including how each handles credits, markup, invoices, and automatic client charging.

Yes. If your goal is “we buy the underlying usage once, then centrally bill each client for their sends/SMS/credits plus our services and markup”, there are a few strong options.

Best fits

*HubWho is more of a centralized agency billing/operations layer than a communications platform itself.

1. HighLevel — probably the closest match

HighLevel is particularly well suited to the model you're describing.

Its agency billing system supports sub-accounts, agency wallets, usage-based charges, client rebilling, markups, and reselling services. The wallet can fund things such as phone/SMS, email, AI usage and other usage-based services. You can then configure rebilling so the client pays the usage cost plus your markup. HighLevel Support Portal HighLevel Support Portal

For example, you could structure a client as:

• $500/month — management/services
• $100/month — included email/SMS credits
• SMS overage — $X per message
• Email overage — $X per 1,000 sends
• AI usage — $X per unit
• Additional services — one-off or recurring charges

That makes HighLevel my first choice if the actual messaging/CRM platform is part of what you're selling.

2. Growtheon — interesting if billing/white-label SaaS is the priority

Growtheon explicitly markets automated SMS, email and AI usage rebilling. It meters usage per client/sub-account and invoices monthly through Stripe, while allowing agencies to set their own pricing and markup. Growtheon

I'd investigate this one if you don't need the breadth of HighLevel and primarily want a white-label SaaS + usage-metering business model.

3. XUNA AI — particularly compelling for AI + communications

XUNA AI is built around selling credits across Voice, SMS, Chat and CRM. It allows agencies to establish their own pricing/markups and bill clients on usage, a flat retainer, or a hybrid model. XUNA AI

This is more compelling if your "sends and credits" include AI agents, voice minutes, conversations, etc., rather than just conventional email marketing.

4. HubWho — worth considering as the billing layer

HubWho takes a different approach: it's designed to sit above your existing agency software and handle recurring/one-off invoices, payments, client portals, wholesale-vs-retail pricing and per-client margin. HubWho

This could be the better architecture if you already have your preferred CRM/email/SMS stack and don't want to migrate everything into HighLevel.

What I'd choose

If you tell me what you're currently using to send email/SMS (e.g. HubSpot, GoHighLevel, Mailgun, Twilio, SendGrid, Klaviyo, etc.), I can narrow this down considerably.

The key distinction is whether you want:

1. One platform that actually provides the email/SMS infrastructure + CRM + client billing → HighLevel
2. A white-label SaaS where usage/credits are the core billing unit → Growtheon / XUNA
3. A centralized billing system that sits on top of several existing tools → HubWho

If your specific requirement is “one agency invoice per client containing SMS credits + email sends + software + labor/services, with automatic usage pulled from multiple platforms”, that's a slightly different—and more interesting—category.

I'd investigate this one if you don't need the breadth of HighLevel and primarily want a white-label SaaS + usage-metering business model.

3. XUNA AI — particularly compelling for AI + communications

XUNA AI is built around selling credits across Voice, SMS, Chat and CRM. It allows agencies to establish their own pricing/markups and bill clients on usage, a flat retainer, or a hybrid model. XUNA AI

This is more compelling if your "sends and credits" include AI agents, voice minutes, conversations, etc., rather than just conventional email marketing.

4. HubWho — worth considering as the billing layer

HubWho takes a different approach: it's designed to sit above your existing agency software and handle recurring/one-off invoices, payments, client portals, wholesale-vs-retail pricing and per-client margin. hubwho.com

This could be the better architecture if you already have your preferred CRM/email/SMS stack and don't want to migrate everything into HighLevel.

What I'd choose

If you tell me what you're currently using to send email/SMS (e.g. HubSpot, GoHighLevel, Mailgun, Twilio, SendGrid, Klaviyo, etc.), I can narrow this down considerably.

The key distinction is whether you want:

If you mean an agency platform where you have one master account, manage multiple clients, and rebill them for email sends, SMS credits, usage, or services, you’ll want something with multi-tenant/client sub-accounts + usage metering + reseller/white-label billing.

Here are the strongest options:

Best fits by agency model

1. “We sell marketing packages”

Example:

• $499/mo client plan
• Includes 20,000 emails
• Includes 1,000 SMS credits
• Extra usage billed automatically

Look at:

• HighLevel
• Acelle Mail
• Aledamail

These are closest to the SaaS-reseller model.

2. “We need to pass through SMS/email costs”

Example:

• Client A uses 8,500 SMS credits
• Client B uses 42,000 SMS credits
• We invoice each separately

Look at:

• SlickText for SMS credit management SlickText
• XUNA AI for broader usage-based communication services XUNA AI

3. “We want our own branded SaaS”

Example:

• Clients log into app.youragency.com
• They see your logo
• You set your own pricing
• You keep the margin

Look at:

• HighLevel
• Acelle Mail
• XUNA AI XUNA AI

Features I’d require before choosing

• ✅ Client sub-accounts/workspaces
• ✅ Per-client usage reporting
• ✅ SMS/email credit pools
• ✅ Automatic overage charging
• ✅ Stripe integration
• ✅ White-label portal
• ✅ Ability to bundle services (software + management + usage)
• ✅ API/webhooks if you want custom billing

A common agency stack is:

• HighLevel → client CRM, automations, campaigns
• Stripe → subscriptions and invoicing
• Twilio/SendGrid/AWS SES/etc. → underlying usage costs
• Usage dashboard → track and markup consumption

If your primary goal is “one invoice to us, many invoices to clients with SMS/email usage markup”, I’d narrow the shortlist to HighLevel, Acelle Mail, SlickText, and XUNA AI depending on whether your main product is marketing automation, email, SMS, or AI services.

If you want to centrally bill clients for email sends, SMS credits, and managed marketing services, you’re generally looking for one of three models:

1. Agency SaaS platforms with usage rebilling (best for marketing agencies)
2. White-label messaging platforms (best if SMS/email is a product you resell)
3. Agency billing/client management tools + usage tracking (best if you invoice manually)

Here are the strongest options:

1. HighLevel — probably the closest all-in-one agency answer

gohighlevel.com

HighLevel is commonly used by agencies that want to sell a branded marketing platform. It supports:

• Client sub-accounts
• Agency-controlled billing
• Usage wallets
• SMS/email/phone usage charges
• Markups on services
• SaaS-style plans

Its wallet system is designed so the agency funds usage and can rebill clients for services like SMS, email, and phone activity. HighLevel Support Portal

Good fit if your offer looks like:

"$499/month marketing system + included credits + overages"

2. SlickText — strong for SMS credit resale

slicktext.com

SlickText has an agency/reseller program where agencies can buy message credits at reseller rates, package SMS into their own services, and manage multiple client accounts. SlickText

Useful if you sell:

• SMS campaigns
• Appointment reminders
• Lead follow-up texting
• Local business marketing packages

It is more SMS-focused than a full agency operating system.

3. White-label SMS providers — best if messaging itself is the product

For a "we are the platform" approach:

• smstools.com offers white-label SMS reselling, wholesale pricing, sub-accounts, and the ability to set your own client pricing. Smstools
• globvoice.com provides white-label messaging across SMS, email, WhatsApp, and voice with client management and reseller pricing models. GlobVoice

These are better when your agency wants to say:

"We provide your messaging platform"

rather than:

"We manage your marketing."

4. Combine billing software + marketing tools

If you already have your preferred email/SMS stack, you can use a billing layer:

• Stripe Billing
• Chargebee
• Recurly
• Agency management platforms

Track:

• Monthly retainer
• Included sends/credits
• Overages
• Setup fees
• Managed service hours

This is more flexible but requires more setup.

My shortlist by agency type

Full-service digital marketing agency
→ HighLevel

SMS marketing agency
→ SlickText or SmsTools

White-label SaaS agency
→ HighLevel SaaS mode or a white-label messaging provider

Agency with custom pricing packages
→ Stripe Billing + usage tracking + your existing tools

A common agency setup is:

• HighLevel as the client-facing platform
• Stripe for recurring billing
• SMS/email costs passed through via usage
• Fixed monthly service fee on top

That gives you predictable recurring revenue while keeping variable sending costs covered.

Full-service digital marketing agency
→ HighLevel

SMS marketing agency
→ SlickText or SmsTools

White-label SaaS agency
→ HighLevel SaaS mode or a white-label messaging provider

Agency with custom pricing packages
→ Stripe Billing + usage tracking + your existing tools

A common agency setup is:

• HighLevel as the client-facing platform
• Stripe for recurring billing
• SMS/email costs passed through via usage
• Fixed monthly service fee on top

That gives you predictable recurring revenue while keeping variable sending costs covered.

If your goal is “one agency account pays the wholesale costs, while clients are automatically charged for their email sends, SMS usage/credits, and other services”, there are a few strong options—but HighLevel is probably the closest fit.

Best fits

1. HighLevel — closest to what you're describing

gohighlevel.com

HighLevel has an Agency Wallet + sub-account rebilling model. Your agency funds the wallet, clients consume services, and HighLevel can charge the client's sub-account for the usage. You can either pass through the cost or add your own markup. HighLevel Support Portal HighLevel Support Portal

It covers:

• Email sends — LC Email usage can be rebilled.
• SMS/MMS — phone-system usage can be rebilled.
• Phone numbers and calling
• Email validation
• AI usage
• WhatsApp
• Workflow/premium usage
• Various other resellable services.

Importantly, HighLevel's current plans distinguish between rebilling at cost and rebilling with markup. Markup-based rebilling is available on the higher Agency Pro tier, while supported services can be rebilled without markup on the $297/$497 plans. HighLevel Support Portal

That makes the model something like:

Your agency → HighLevel wholesale wallet → Client sub-account → client card

For example, you could configure:

Client A: $0.80 / 1,000 emails
Client A: $0.015 / SMS segment
Client A: $X/month CRM/platform
Client A: $Y/month SEO
Client A: $Z/month management service

The agency can then retain the markup.

One caveat: HighLevel's current phone/SMS pricing includes a 5% location-level markup on certain carrier/A2P charges, before any additional agency rebilling markup. HighLevel Support Portal

2. Vendasta — better if “services” are the bigger part

vendasta.com

Vendasta is particularly interesting if you want to operate more like a white-label marketplace/reseller than just an email/SMS platform.

Its billing system lets agencies:

• Create recurring subscriptions
• Create one-time charges
• Add custom services
• Set wholesale vs. retail pricing
• Automatically invoice clients
• Automatically charge cards
• Sell products from its marketplace
• Brand the client-facing billing experience. Vendasta Support Vendasta

So if your business model is:

“We sell clients marketing software + email + SMS + SEO + reputation management + websites + managed services”

I'd seriously consider Vendasta.

But if usage-based email/SMS billing is the core requirement, I'd lean toward HighLevel.

3. Mailgun — good infrastructure, not really client billing

mailgun.com

Mailgun supports subaccounts and lets you track/control sending usage by customer, which can be useful for an agency building its own billing layer. Mailgun Documentation Mailgun

The major limitation is that Mailgun subaccounts aren't separately billed. Usage rolls up to the primary account. Mailgun Documentation

So you'd need something like:

Mailgun → usage API → your billing system/Stripe → client invoice

That's powerful if you're building your own platform, but considerably more work than HighLevel.

My recommendation

If you're looking for software you can adopt rather than build, I'd rank them:

1. HighLevel — best match for central agency billing + email/SMS usage + markup + client subaccounts + SaaS.
2. Vendasta — best if you're going to sell a broad catalog of software/services and want sophisticated white-label commerce.
3. Mailgun + Stripe/custom billing — best if you're building your own platform and need granular control over usage billing.

The key distinction: if by “services” you mean things like SEO, websites, AI, reputation management, ad management, etc., Vendasta becomes much more compelling. If you mean email sends + SMS credits + CRM/automation + your own recurring agency fee, HighLevel is the much more natural fit. HighLevel Support Portal Vendasta

If you tell me what you're currently using for email/SMS (e.g. Mailgun, SendGrid, Twilio, Brevo, etc.) and whether clients should pay automatically by card, I can narrow this down to the best 2–3 architectures.

mailgun.com

Mailgun supports subaccounts and lets you track/control sending usage by customer, which can be useful for an agency building its own billing layer.

The major limitation is that Mailgun subaccounts aren't separately billed. Usage rolls up to the primary account.

So you'd need something like:

Mailgun → usage API → your billing system/Stripe → client invoice

That's powerful if you're building your own platform, but considerably more work than HighLevel.

My recommendation

Yes. If your goal is one agency account that pays the underlying costs, then bills each client for SMS, email sends/credits, and your own services—ideally with markup, there are a few strong options.

Best fits

1. HighLevel — probably the closest match

gohighlevel.com

This is the one I'd investigate first for your use case.

HighLevel has an Agency Wallet that pays for usage-based services, while client sub-accounts can be charged for the usage they generate. Its current documentation specifically describes rebilling for Phone/SMS, Email, AI and other usage-based services, including the ability to add an agency markup on the Agency Pro plan. HighLevel Support Portal HighLevel Support Portal

So you can essentially structure:

Client → pays your agency → agency pays HighLevel → usage is tracked per client

For example:

• Client A: $299/mo marketing service
• SMS: $0.XX per message + your markup
• Email: $X per 1,000 sends + your markup
• AI usage: pass-through + markup
• Other services: recurring or one-time charges

HighLevel's documentation also confirms that client invoices can be branded as the agency's invoices, with the money going through the agency's connected Stripe account. HighLevel Support Portal

The important distinction is plan level: HighLevel currently says rebilling without markup is available on the $297/$497 plans, while rebilling with agency markup is available on the $497 Agency Pro plan. HighLevel Support Portal

2. SlickText — if SMS is the core product

slicktext.com

SlickText is particularly interesting if you're primarily selling SMS marketing as a managed service.

It explicitly supports agencies putting multiple brands under one account, consolidating billing under the agency, distributing message credits to individual clients, monitoring their usage, and setting automatic credit refills. SlickText

I'd consider this if your model is something like:

"We manage SMS marketing for 50 businesses, and each business gets its own pool of credits."

It's less of a complete CRM/agency operating system than HighLevel, though.

3. Vendasta — better for a broader service catalog

vendasta.com

Vendasta is strong if your agency wants to sell packages containing lots of different services, rather than primarily selling communication usage.

It provides a product catalog connected directly to billing, supports recurring and one-time charges, and uses Stripe Connect for client payments. It also lets agencies package marketplace products and their own services under their brand. Vendasta

Think:

$799/month Local Growth Package

• Website
• SEO
• Reputation management
• SMS
• Email
• Listings
• Reporting
• Managed services

That's more Vendasta's territory.

4. Clientjoy — good billing layer, but not my first choice for usage

clientjoy.io

Clientjoy is more oriented toward agency CRM, proposals, contracts, invoices and client management. It has white-label client portals and branded invoicing. ClientJoy

I'd use it alongside a communication platform if your primary requirement is sophisticated agency billing rather than having the communication infrastructure itself handle metering.

My recommendation

If what you're describing is:

"We want to buy SMS/email capacity centrally, allocate it to clients, track their consumption, charge them automatically, add our margin, and also charge for our managed services."

I'd rank them:

1. HighLevel — best overall fit
2. SlickText — best if SMS/credits are the centerpiece
3. Vendasta — best if you're building a broad reseller/service marketplace
4. Clientjoy — best as a billing/client-management layer rather than the usage engine

HighLevel is unusually well aligned with the exact "agency wallet → client usage → rebill with markup" model. Its current documentation even describes SMS/email/phone usage as wallet-funded and rebillable to individual sub-accounts. HighLevel Support Portal HighLevel Support Portal

If you tell me what you're selling (e.g. SMS + email + voice + AI + marketing services) and roughly how many clients, I can narrow this down to the 2–3 platforms with the best unit economics, including how much markup you could realistically put on each usage type.

It explicitly supports agencies putting multiple brands under one account, consolidating billing under the agency, distributing message credits to individual clients, monitoring their usage, and setting automatic credit refills. SlickText

I'd consider this if your model is something like:

"We manage SMS marketing for 50 businesses, and each business gets its own pool of credits."

It's less of a complete CRM/agency operating system than HighLevel, though.

3. Vendasta — better for a broader service catalog

vendasta.com

Vendasta is strong if your agency wants to sell packages containing lots of different services, rather than primarily selling communication usage.

It provides a product catalog connected directly to billing, supports recurring and one-time charges, and uses Stripe Connect for client payments. It also lets agencies package marketplace products and their own services under their brand. Vendasta

Think:

$799/month Local Growth Package

• Website
• SEO
• Reputation management
• SMS
• Email
• Listings
• Reporting
• Managed services

That's more Vendasta's territory.

4. Clientjoy — good billing layer, but not my first choice for usage

clientjoy.io

Clientjoy is more oriented toward agency CRM, proposals, contracts, invoices and client management. It has white-label client portals and branded invoicing. clientjoy.io

I'd use it alongside a communication platform if your primary requirement is sophisticated agency billing rather than having the communication infrastructure itself handle metering.

My recommendation

If what you're describing is:

If you mean agency software where you pay the vendor centrally, then charge each client for their email sends, SMS usage/credits, and additional services—ideally with your own markup, the strongest fit I found is gohighlevel.com.

Best fits

1. HighLevel — closest match

HighLevel is unusually well suited to exactly what you're describing.

Its Agency Wallet centrally pays for usage-based services, while rebilling lets you charge the corresponding client/sub-account. You can rebill at cost or, on the higher-tier setup, add your own markup. Supported usage includes phone/SMS and email, plus various other services. HighLevel Support Portal HighLevel Support Portal

The current Pro/SaaS setup also supports client wallets, where clients can add funds and those credits are used for email/phone usage. HighLevel Support Portal

HighLevel's current pricing documentation says:

• $297/mo Unlimited — unlimited sub-accounts and rebilling without markup for supported services.
• $497/mo Agency Pro — adds rebilling with markup and SaaS Mode. HighLevel Support Portal HighLevel Support Portal
• SaaS Mode lets you create your own packages, set pricing, include credits, and automatically bill clients through the agency's Stripe setup. GoHighLevel

So you could structure something like:

Client A: $299/month
Includes 10,000 emails + 1,000 SMS credits
Additional email: $X/1,000
Additional SMS: $X/segment
Managed campaigns: $500/month
AI/service add-ons: $X

And have the platform handle much of the underlying usage accounting/billing.

2. Vendasta — better if "services" are the bigger business

vendasta.com is worth considering if by services you mean things like SEO, reputation management, listings, ads, websites, social media, etc.

Its model is more explicitly built around agencies reselling a catalog of third-party services/products to clients, rather than primarily being an email/SMS automation platform. CRM Reviews CRM Reviews

So I'd choose:

• HighLevel → you're selling marketing automation + email + SMS + CRM + services
• Vendasta → you're selling a bundle of digital marketing services/products and want a marketplace/reseller infrastructure.

My recommendation

For your specific wording—"bill clients for sends, SMS credits and services centrally"—I'd start with HighLevel.

The important distinction is that you're not merely looking for invoicing software. You want usage metering → client attribution → wallet/credit management → rebilling → markup → centralized agency billing. HighLevel has those pieces built into the same ecosystem. HighLevel Support Portal HighLevel Support Portal

If you tell me what you're actually selling (e.g. email marketing, SMS campaigns, newsletters, AI agents, social posting, SEO, PPC), I can narrow this down to the 3 best platforms and show exactly how each would handle your client billing model.

For your specific wording—"bill clients for sends, SMS credits and services centrally"—I'd start with HighLevel.

If you mean an agency platform where you can centrally manage clients and rebill them for email sends, SMS credits, phone usage, and other services, these are the strongest fits:

My shortlist by agency model

If you sell “marketing automation as a service”

Choose HighLevel. It is closest to an agency reseller model:

• Create one account per client
• Give each client their own CRM/workspace
• Charge a monthly SaaS fee
• Add markup on SMS/email/call consumption
• Manage billing centrally HighLevel Support Portal

If you run a service agency (design, marketing ops, fulfillment)

Choose ManyRequests:

• Retainers
• Packages
• Credits/hours
• Client portals
• Recurring invoices ManyRequests

If your main variable cost is SMS

Choose SlickText or pair an SMS provider with your billing system:

• Buy message volume centrally
• Allocate credits to clients
• Track consumption
• Pass through costs or add margin SlickText

A common agency stack

A lot of agencies end up with:

• CRM + delivery: HighLevel
• Payments: Stripe
• Usage billing: HighLevel wallets or a metering tool
• Accounting: QuickBooks/Xero
• Client portal: HighLevel, ManyRequests, or a custom portal

The key feature to look for is metered billing: the ability to define units like:

• 1,000 SMS credits/month included
• $0.01 per SMS overage
• Email sends priced per thousand
• AI/API usage credits
• Setup fees + recurring management fee

If you tell me your agency type (SMS marketing, email marketing, lead gen, SaaS reseller, CRM implementation, etc.) and approximate client count, I can narrow this to the best 2–3 options.

If your goal is specifically “one agency account pays the wholesale costs, then we centrally charge clients for email sends, SMS credits/usage, and our own services”, there are two standouts:

1. HighLevel — best fit for usage-based rebilling

gohighlevel.com

This is probably the closest match to what you're describing.

• Agency Wallet: your agency funds usage centrally, with automatic wallet replenishment. HighLevel Support Portal
• Email rebilling: you can pass email costs to individual sub-accounts and, on supported plans, apply a markup. HighLevel Support Portal HighLevel Support Portal
• SMS/phone rebilling: HighLevel can automatically bill clients for phone/SMS usage, including an agency markup. HighLevel Support Portal HighLevel Support Portal
• SaaS/reselling: you can package the platform/services into client subscriptions and charge clients through the agency setup. HighLevel Support Portal
• You can also monitor usage by sub-account and set wallet usage thresholds. HighLevel Support Portal

The important distinction: HighLevel is strongest if the communications themselves are happening inside HighLevel. You essentially turn your agency into the billing layer sitting above the individual client accounts.

For example:

Client A → $299/mo platform + $30 SMS + $8 email usage + $500 management
Client B → $499/mo platform + $75 SMS + $20 email usage + $1,000 management
Agency → pays HighLevel wholesale usage centrally

That's very close to your use case.

2. Vendasta — best for broader agency services

vendasta.com

Vendasta is more oriented toward agency commerce/reselling, rather than specifically communications usage.

Its billing system lets you combine products and services into client subscriptions, automatically generate invoices, collect payments, and sell everything under your agency's brand. Vendasta Vendasta Support

It supports:

• recurring subscriptions
• one-time/custom charges
• setup fees
• consolidated client invoices
• wholesale vs. retail pricing
• white-label client experience
• agency services + third-party products in one billing ecosystem Vendasta Vendasta Support

Vendasta also has email/SMS marketing functionality, although SMS is an add-on and its model is more product/subscription billing than HighLevel's granular usage rebilling. Vendasta Documentation

How I'd choose

My recommendation

If sends/SMS are a major component of what you're billing for, I'd start with HighLevel. Its rebilling architecture is specifically designed around an agency paying for client usage and passing that cost—with markup if desired—back to the client. HighLevel Support Portal HighLevel Support Portal

If you're trying to build a broader “agency operating system” where the invoice might contain website + SEO + ads + software + email + SMS + consulting + other third-party services, Vendasta deserves a serious look.

If you tell me what you're currently using for email/SMS (e.g. Twilio, Mailgun, SendGrid, Amazon SES, etc.) and whether you want the client to see itemized usage or just one monthly invoice, I can narrow this down to the best 3–5 options, including platforms that let you keep your existing sending infrastructure.

If you mean an agency platform where you can centrally manage clients and charge them for usage like email sends, SMS credits, phone usage, plus your own recurring services, the strongest options are:

1. GoHighLevel — probably what you're looking for

GoHighLevel is particularly well suited to this model.

Its Agency Pro ($497/mo) tier includes email/phone/text rebilling and SaaS Mode. You pay HighLevel for usage through the agency wallet, then HighLevel can charge the client's sub-account for its usage. You can also add a markup, so the client could pay, for example, $0.015 per SMS when your underlying cost is $0.01. HighLevel Support Portal HighLevel Support Portal

It also has SaaS Wallets, where clients can have balances that are used for phone/email usage, including automatic card recharges. HighLevel Support Portal

That makes it possible to structure something like:

• Client A — $499/mo marketing service
• 10,000 email credits — $25
• 1,000 SMS credits — $20
• Phone usage — $15
• Additional automation/service — $100
• One client relationship and centralized billing infrastructure

HighLevel explicitly supports both usage-based rebilling and fixed-price SaaS/service reselling, which is the combination you're describing. HighLevel Support Portal

gohighlevel.com

2. Vendasta — better if you're really building a service marketplace

Vendasta is worth considering if your model is less "we run the marketing infrastructure" and more "we sell clients a bundle of marketing products/services."

Its strength is the marketplace/reseller model: agencies can package multiple third-party products and services, present them under their brand, and manage client billing. SuiteDash SaaSComparer

I'd lean Vendasta if you want to sell things like:

• SEO
• Reputation management
• Websites
• Listings
• Advertising
• Social
• Other third-party services

I'd lean HighLevel if the core thing you're selling is CRM + automation + email + SMS + funnels + communications, with usage passed through to clients.

vendasta.com

My recommendation

For the specific phrase "bill clients for sends, SMS credits and services centrally", I'd start with GoHighLevel.

The important distinction is that you don't just want a normal agency CRM with Stripe invoicing. You want metered usage + wallets/credits + rebilling + markup + recurring services. HighLevel is unusually well aligned with that architecture. HighLevel Support Portal HighLevel Support Portal

If you tell me what you're currently using for email/SMS (e.g. Twilio, Mailgun, SendGrid, Brevo, etc.) and roughly how many clients you have, I can narrow this down to the 3 best platforms and show exactly how the billing would flow from your cost → client usage → your markup → invoice.

If your goal is one agency-level account that pays wholesale costs, then bills each client for their actual email sends, SMS credits, and your own services, there are a few strong options—but HighLevel is probably the closest fit.

Best fits

1. HighLevel — probably the closest match

HighLevel is specifically designed around the agency/SaaS model. The agency has an Agency Wallet that pays for usage, while supported costs can be rebilled to individual sub-accounts, either at cost or with a markup. Supported usage includes phone/SMS and email, among other services. HighLevel Support Portal HighLevel Support Portal

For example, you could structure a client like:

• $500/month managed marketing fee
• 10,000 email sends included
• $X per additional 1,000 emails
• $X per SMS
• $X per phone minute
• $100/month Google Ads management
• $250/month SEO
• AI usage billed based on consumption

HighLevel's SaaS Mode lets you create plans, set pricing, add Twilio credits, and automatically rebill usage. GoHighLevel

Importantly, email rebilling is currently supported, including markup functionality on the higher-tier agency plans. HighLevel Support Portal

The current pricing page lists Agency Unlimited at $297/month and Agency Pro at $497/month, with SaaS Mode on Pro. GoHighLevel

I'd choose HighLevel if the actual delivery platform is also going to be your CRM/marketing automation platform.

2. Vendasta — better if you're primarily reselling services

vendasta.com is more of an agency commerce/reseller platform.

Its strength is combining:

products + services + subscriptions + invoices + payments + client portal

Vendasta creates separate wholesale and retail subscriptions, so you can see what you pay versus what your client pays. Vendasta Support

It also supports recurring charges, one-time charges, setup fees, taxes, custom services, and branded invoicing. Vendasta Vendasta

The Marketplace gives agencies access to 250+ products/services that can be packaged and resold under the agency's brand. Vendasta Vendasta Support

So Vendasta makes more sense if your business looks like:

Agency
→ Website
→ SEO
→ Paid ads
→ Reputation management
→ Email marketing
→ SMS
→ Other SaaS products
→ Managed services

…and you want the client to receive one consolidated bill.

My recommendation

If you're specifically asking:

"I want to buy email/SMS capacity centrally and automatically pass those costs, plus my agency services, onto each client."

I'd rank them:

1. HighLevel — best for usage-based SMS/email rebilling + agency SaaS
2. Vendasta — best for broader agency service/product reselling and consolidated billing
3. Stripe + custom usage metering — best if you already have your own software and want complete control

The important distinction is that HighLevel actually understands communication usage as a billable agency resource, whereas a generic invoicing system generally requires you to build the usage-metering layer yourself. HighLevel explicitly separates agency wallet costs from client rebilling. HighLevel Support Portal

If you tell me what software you're currently using for email/SMS (e.g. GoHighLevel, Twilio, SendGrid, Mailgun, Klaviyo, HubSpot, etc.), I can narrow this down to the best 3 platforms and show exactly how the client billing would flow, including where you can add your markup.

If your goal is one agency account that pays the wholesale costs, tracks each client’s usage, and automatically bills clients for email sends, SMS credits, and other services, HighLevel is probably the strongest fit.

Best options

1. HighLevel — closest match

HighLevel has an Agency Wallet + client/sub-account wallets + rebilling system. Your agency can fund usage centrally, while the platform tracks consumption by client and charges the client's wallet for eligible usage. You can rebill at cost or with a markup. help.gohighlevel.com

That covers things such as:

• Email sends
• SMS/MMS
• Phone usage
• AI usage
• WhatsApp
• Email validation
• Premium workflow usage
• Other resold services

For example, you could structure something like:

Client A → $99/month platform fee

• $20 SMS credits
• $15,000 email sends
• $50 automation usage
• $500 managed services

HighLevel can handle the usage-based components through its wallet/rebilling architecture, while its reselling functionality handles additional services. It also supports usage-based Marketplace charges with agency markups and client-level limits. help.gohighlevel.com

One particularly useful feature is that SMS/email usage can be charged to the client wallet automatically, rather than your team having to calculate usage and manually invoice every month. help.gohighlevel.com

Important caveat: HighLevel's current plans matter. Rebilling without markup starts on the $297/month plan, while rebilling with your own markup is available on the $497/month Agency Pro plan. help.gohighlevel.com

2. Vendasta — better if you're selling lots of services

Vendasta is worth considering if your business model is more like a white-label agency marketplace.

It lets you create a catalog of services, sell subscriptions, generate recurring invoices, charge setup/custom fees, and collect payment through an integrated Stripe-based billing system. www.vendasta.com

I'd favor Vendasta if your clients are buying things like:

• SEO
• websites
• reputation management
• advertising
• social media
• marketing automation
• consulting/services

rather than primarily consuming SMS/email credits.

My recommendation

If the core requirement is:

"We buy communications/automation capacity centrally and resell it to dozens/hundreds of clients with our own pricing."

I'd start with HighLevel.

If the requirement is:

"We want a white-label agency storefront where clients buy lots of different marketing services and receive consolidated invoices."

I'd look harder at Vendasta.

And if you mean something more specific—e.g. you already use Twilio/SendGrid/Mailgun and want software that meters each client's sends/SMS credits and puts everything onto one monthly agency invoice—there are some more specialized options I'd compare against HighLevel.

If you mean an agency platform where you can centrally manage clients and recharge them for email sends, SMS credits, messaging usage, and other services, the best options usually fall into two categories:

1. All-in-one agency SaaS platforms with built-in rebilling
2. White-label messaging/reseller platforms with credit wallets

Here are the strongest fits:

My shortlist by use case

If you are a marketing agency selling campaigns

HighLevel is probably the closest match. It is designed around the agency relationship:

• one master account
• multiple client accounts
• client-specific pricing
• SMS/email usage rebilling
• SaaS-style subscriptions
• automated wallet charging HighLevel Support Portal

If your main product is "we sell SMS/email credits"

Look at:

• Text Global
• SmsTools

These behave more like a telecom reseller:

• buy wholesale credits
• allocate credits to clients
• add your margin
• provide a branded portal Text Global Smstools

If you need to bill for mixed services

For example:

• £500/month marketing retainer
• - SMS usage
• - email sends
• - ad management
• - design tasks

A combination often works best:

• Stripe + agency billing platform (e.g., ManyRequests)
• messaging provider with API usage tracking
• automated monthly invoicing

Features I would prioritise

For an agency model, look for:

• Client subaccounts
• Usage-based billing
• Credit wallets
• Markup rules per client
• Prepaid and postpaid options
• Automatic invoice generation
• Stripe integration
• White-label client portal
• Usage reports by client/campaign/channel

If you are UK-based and selling marketing services, I would typically compare HighLevel vs a white-label SMS platform (Text Global/SmsTools) vs Stripe + an agency billing layer depending on whether your revenue is mostly software, messaging volume, or managed services. Text Global Smstools HighLevel Support Portal

Yes. If your goal is “the agency pays the wholesale usage centrally, then bills each client for their sends/credits + your services, ideally with markup”, there are a few strong options.

Best fits

🥇 HighLevel is probably the closest match

HighLevel is particularly well suited if you're selling CRM + email + SMS + automation + managed services as one agency offering.

Its current billing system has an Agency Wallet for usage-based services. The agency funds the wallet, and usage can include SMS/phone, email, AI, workflow features, etc. HighLevel can then rebill sub-accounts, including applying a markup. help.gohighlevel.comhelp.gohighlevel.com

For example, you could structure:

Client pays you $499/month

• $0.XX/SMS
• $X/1,000 emails
• $Y for additional services

HighLevel handles the usage accounting and client rebilling rather than you having to manually calculate every client's consumption. Its current documentation specifically describes charging clients for usage and adding a markup. help.gohighlevel.comhelp.gohighlevel.com

Email rebilling is explicitly supported, with markup available on the higher agency tier; HighLevel currently documents email usage at $0.675/1,000 emails and markup-enabled email rebilling on the $497/month plan. help.gohighlevel.com

It also supports reselling fixed-price services alongside usage-based rebilling—for example, you can sell a service to a sub-account at your own client-facing price. help.gohighlevel.com

HighLevel official site

🥈 Vendasta if you're more of a “digital services reseller”

Vendasta is potentially better if your model is:

Client → your agency → bundle of marketing services/software

rather than primarily running the client's communications through your own CRM.

Vendasta lets agencies create their own products/services, package them, and invoice clients for recurring or one-time charges. Its billing system integrates the product catalog with billing, and it supports branded invoices and Stripe Connect. www.vendasta.com

So you could have:

• Website management — $299/mo
• SEO — $499/mo
• Email marketing — $199/mo
• SMS — usage-based
• Social media — $399/mo
• Managed services — $750/mo

all presented as one agency relationship.

Vendasta official site

My recommendation

If sends/SMS credits are a major component of what you're selling, I'd start with HighLevel.

If you're essentially building a white-label digital agency marketplace, where email/SMS is only one of many products you're reselling, I'd look harder at Vendasta.

The important distinction is:

HighLevel:

“I operate the communications/CRM platform for my clients and want to automatically meter + rebill usage.”

Vendasta:

“I sell a portfolio of digital products and services to clients and want centralized catalog, fulfillment, invoicing and payments.”

If you tell me what you're currently using for email + SMS (e.g. Twilio, Mailgun, SendGrid, Resend, HighLevel, etc.) and whether clients should see the actual usage line items, I can narrow this down to the 3–5 best platforms and show exactly how the billing flow would work.

If you mean an agency platform where you can centrally charge clients for email sends, SMS usage/credits, and your own services (retainers, add-ons, setup fees, etc.), you’ll want something with sub-accounts, usage metering, wallets/credits, rebilling, and Stripe-style invoicing.

Here are the strongest options:

My shortlist by agency model

1. You sell marketing automation + SMS/email as a managed service
→ HighLevel is usually the closest match. It was built around the idea of agencies owning client accounts and rebilling communication usage. You can charge:

• $X/month platform fee
• SMS/email usage markup
• automation packages
• onboarding fees
• add-on services

help.gohighlevel.com

2. You are an agency delivering services (SEO, creative, ads, dev, consulting) and want credits
→ ManyRequests is a better billing layer:

• monthly retainers
• prepaid credits
• service packages
• usage tracking
• client self-service billing

www.manyrequests.comwayfront.comhelp.gohighlevel.com

3. You mainly need SMS resale
→ SlickText has agency-specific SMS billing workflows:

• central agency account
• client brands
• message credit allocation
• flexible billing structures

www.slicktext.com

A common agency stack

A lot of agencies combine:

• HighLevel → client CRM + SMS/email delivery + usage tracking
• Stripe Billing → payment collection
• ManyRequests/Wayfront → service catalog and fulfillment billing

For your specific requirement — “bill clients centrally for sends, SMS credits and services” — I’d start by evaluating HighLevel vs ManyRequests. HighLevel is stronger if the billable items are communication usage; ManyRequests is stronger if the billable items are agency services and credits. www.manyrequests.comwayfront.comhelp.gohighlevel.com

A few details would narrow this down:

1. Are you billing marketing clients (CRM/SMS/email campaigns) or a broader agency service catalog?
2. Do you want clients to see their own usage dashboard?
3. Do you need automatic markup on SMS/email costs, or just pass-through billing?

If your goal is specifically “one agency account pays the vendors, then we centrally bill each client for their email sends, SMS credits/usage, and additional services”, HighLevel is probably the strongest fit right now.

Best options

1. HighLevel — closest match

HighLevel is unusually well aligned with the model you're describing.

The agency has an Agency Wallet that pays for usage such as phone/SMS and email. You can then rebill the individual client/sub-account for the usage they generated. On the higher-tier plans, you can add a markup rather than simply passing through cost. help.gohighlevel.comhelp.gohighlevel.com

For example:

Client A → 10,000 emails + 2,000 SMS → HighLevel charges your agency → HighLevel automatically charges Client A's wallet according to your pricing.

You can also give clients complimentary/monthly credits, set automatic wallet recharges, and charge the client's card when their balance needs replenishing. help.gohighlevel.com

The current pricing structure is particularly relevant:

• $297/mo Unlimited: rebill phone/email at cost for supported services
• $497/mo Agency Pro: adds SaaS Mode, automated sub-account creation, and phone/email rebilling with markup. www.gohighlevel.comwww.gohighlevel.comhelp.gohighlevel.com

HighLevel also supports selling the broader platform as a SaaS product—so you can bundle things like CRM, automation, reputation management, SMS, email, etc. into your own client plans. www.gohighlevel.com

For your use case, I'd start by evaluating the $497 Agency Pro tier.

2. Vendasta — better if “services” are the main product

Vendasta is worth considering if you're less interested in building your own CRM/automation platform and more interested in reselling a catalog of services to clients.

It is designed around the agency/partner model and lets agencies package third-party products under their own offering. Vendasta describes its platform as covering reputation, listings, CRM, messaging/calls, social, and other customer-acquisition services. www.vendasta.com

So I'd think of the distinction as:

HighLevel:

“We're building our own software/service platform for clients.”

Vendasta:

“We're an agency reselling a bunch of software/services to clients.”

3. Stripe + Twilio/other APIs — best if you want a custom billing engine

If your actual requirement is more sophisticated—for example:

• $X per 1,000 emails
• $X per SMS
• $X per WhatsApp message
• monthly platform fee
• one-off implementation fees
• managed-service fees
• different markup per client
• prepaid credits
• automatic top-ups
• consolidated monthly invoices
• usage reporting
• agency-level vendor accounts

…then Stripe Billing + your own usage ledger + Twilio/email provider gives you the most control.

But you're essentially building the part that HighLevel already provides.

My recommendation

If I were choosing specifically for an agency model where you want:

Agency pays wholesale → clients consume usage → clients get billed automatically → you add margin → services are bundled into plans

I'd rank them:

1. HighLevel ⭐⭐⭐⭐⭐
Best out-of-the-box match.

2. Vendasta ⭐⭐⭐⭐
Better if you're primarily reselling many external services.

3. Stripe + APIs ⭐⭐⭐⭐
Best if your billing model is unusual enough that you need complete control.

One important distinction: HighLevel's “rebilling” is primarily usage/service billing, not necessarily a universal invoice engine for arbitrary agency line items. Its current documentation explicitly covers phone, email, AI and other usage, while SaaS/reselling handles packaged products. help.gohighlevel.com

If you tell me what you're currently using for email (SendGrid/Mailgun/SES/etc.), SMS (Twilio/etc.), and what “services” you want to bill, I can narrow this down to the 2–3 platforms that fit your exact billing architecture, including how the money flows from client → agency → vendor.

If your goal is “the agency pays the wholesale communication costs, then centrally bills each client for their SMS/email usage + our services, ideally with markup”, the strongest fit I found is HighLevel.

Best fits

1. HighLevel — probably your closest match

HighLevel is unusually well suited to exactly this model.

Its Agency Wallet lets your agency centrally fund usage-based services. Client sub-accounts can then be charged for the usage they generate. HighLevel currently supports rebilling for things including phone/SMS, email, AI and other usage-based services, with the Pro/SaaS setup allowing you to add your own markup. help.gohighlevel.com

The really useful part is the SaaS Wallet: clients can have their own wallet funded by their card, and SMS/email/phone usage deducts from that wallet. You can set recharge thresholds and apply your pricing/markup. help.gohighlevel.com

HighLevel's current plan structure puts Email/Phone/Text Rebilling and SaaS Mode on the $497/month Agency Pro plan. help.gohighlevel.com

So you could structure something like:

Client A
$499/mo marketing services

• $0.025/SMS
• $0.0015/email
• $99 setup fee
• other recurring services

And have HighLevel handle the underlying usage and client charging rather than your team manually calculating sends every month.

HighLevel billing & rebilling documentation

2. Vendasta — better if you're selling a catalog of services

Vendasta is worth considering if the important part is centralized agency commerce rather than SMS/email being the core billing unit.

It supports recurring invoices, one-time charges, setup fees, taxes, and selling products/services from a centralized catalog. Clients can purchase and pay through your branded experience. www.vendasta.com

So Vendasta makes more sense for:

$299 SEO + $199 reputation + $499 ads + $X software + custom services

whereas HighLevel makes more sense for:

$299 platform + SMS consumption + email consumption + phone consumption + automation/CRM services.

My recommendation

If you're a marketing/automation agency where SMS and email usage are part of what you're reselling, I'd choose:

HighLevel SaaS Pro → client subaccounts → agency wallet → usage rebilling → Stripe → recurring service charges.

That's probably the closest off-the-shelf solution to “one agency bill, many clients, charge each client for exactly what they consume, plus our service fees and margin.” HighLevel explicitly supports both usage rebilling and reselling additional services. help.gohighlevel.com

If you tell me what you're currently using for CRM/email/SMS (e.g. Twilio, Mailgun, HubSpot, GoHighLevel, Klaviyo, etc.) and roughly how many clients you have, I can compare HighLevel vs Vendasta vs Stripe + your existing stack specifically around billing architecture, margins, client wallets/credits, invoices, and automation.

Yes. If the goal is “one agency account pays the underlying usage, while each client gets billed automatically for their SMS, email sends, credits, and other services”, there are a few strong options.

Best fits

My first choice for what you described is HighLevel. Its Agency Wallet centralizes usage costs, while SaaS Mode/rebilling lets you charge individual sub-accounts for usage. HighLevel specifically supports rebilling for Phone/SMS and Email, and Agency Pro allows markup rather than merely passing through cost. help.gohighlevel.com

For example, your agency could have:

• Client A → $0.XX/SMS
• Client A → $X per 1,000 emails
• Client A → $49/month CRM/service fee
• Client A → $100/month automation package
• Client B → different pricing
• All underlying usage → paid from your agency wallet
• Client charges → collected through your connected Stripe account

HighLevel explicitly supports this model: the agency is billed for the usage, then the client is billed for the usage generated by its sub-account. help.gohighlevel.com

It also goes beyond SMS/email. HighLevel currently supports rebilling/reselling things such as AI usage, workflow premium features, email validation, domains, phone services, and other add-ons. help.gohighlevel.com

Where Vendasta fits

Vendasta is arguably better if you're thinking of your agency as a catalog/reseller business rather than primarily a CRM platform.

You can create recurring charges, one-time charges, packages, and custom invoices, and Vendasta connects products/services to its billing system. It also supports branded client-facing purchasing and Stripe-based payments. www.vendasta.com

So I'd think of the distinction as:

• HighLevel: “We operate the marketing/CRM infrastructure for clients and rebill their consumption.”
• Vendasta: “We sell a portfolio of marketing services/products to clients and manage the commercial relationship.”

If you're specifically building a credit-based model

XUNA AI is worth investigating. It explicitly supports agencies billing clients per credit, with usage spanning Voice, SMS, Chat and CRM, while the agency controls its markup. www.xuna.ai

My recommendation

If your model is something like:

Monthly platform fee + SMS credits + email credits + AI credits + managed services

I'd strongly investigate HighLevel first. It is unusually close to having the entire agency → client → usage → markup → Stripe billing chain built into the platform rather than requiring you to stitch together Stripe + Twilio + Mailgun + invoicing software yourself.

One important caveat: HighLevel's exact rebilling/markup availability depends on the agency plan and service. For example, its current documentation says markup-based rebilling for Phone and Email is available on the $497 Agency Pro tier, while the $297 tier supports certain pass-through rebilling. help.gohighlevel.comwww.xuna.ai

If you tell me what you're currently using for CRM/email/SMS (e.g. HubSpot + Twilio + Mailgun, GoHighLevel, Keap, etc.), I can narrow this down to the 3–5 best platforms and show exactly how the client billing flow would work for each.

If your goal is specifically “one agency account pays the vendors, then we centrally bill each client for their email sends, SMS usage/credits, and other services”, the strongest options I’d look at are:

1. HighLevel — probably closest to what you're describing

HighLevel is unusually well suited to this model.

Its Agency Wallet pays for usage-based services centrally. Email, phone/SMS and other usage can then be rebilled to individual client sub-accounts, either at cost or with a markup. HighLevel explicitly supports usage-based rebilling and an agency-level Stripe account for charging clients. help.gohighlevel.com

For example, you could structure a client as:

• $499/month — marketing automation service
• $100 — email credits
• $75 — SMS usage
• $250 — managed campaign services
• $50 — additional software/service
• Total: $974/month

The important part is that HighLevel can handle the usage → client → agency billing relationship, rather than you manually calculating everyone's consumption. Email usage is currently billed per send, and its Phone System handles SMS/MMS usage. help.gohighlevel.com

This would be my first choice if you want the platform itself to be the agency's operating system.

2. Vendasta — better if you're essentially running a service marketplace

Vendasta takes a somewhat different approach.

It's particularly strong if you want to sell clients a bundle of products/services, with wholesale costs on your side and retail pricing on the client side. Vendasta creates separate wholesale and retail subscriptions, so you can see what you pay versus what the client pays. docs.vendasta.comwww.vendasta.com

It also supports:

• recurring client billing
• one-off charges
• custom line items
• automatic payment collection
• consolidated invoices
• branded/white-label billing
• setup fees and taxes
• marketplace products

docs.vendasta.comwww.vendasta.com

So I'd favor Vendasta over HighLevel if your agency sells lots of disparate services—SEO, reputation management, websites, ads, listings, software subscriptions, etc.—and you want a centralized catalog + commerce + billing system.

3. Twilio — best if you want to build your own system

Twilio is different: it's more of an infrastructure component than an agency-management platform.

You can create subaccounts for individual customers, while the main account pays the aggregate Twilio bill. Twilio also has Billing Groups for consolidating multiple accounts and exposes usage data through APIs. www.twilio.com

That's excellent if your architecture is something like:

Your agency software → Twilio → clients

and you want your own:

• usage meter
• credit system
• markup engine
• Stripe billing
• client portal
• invoices
• prepaid wallets

But you're building those pieces yourself.

My recommendation

If you want “agency-friendly billing out of the box”, I'd rank them:

🥇 HighLevel — best for usage-based email/SMS + client rebilling + agency services

🥈 Vendasta — best for selling lots of different services/products and consolidating them into client billing

🥉 Twilio — best for building a custom agency billing/usage platform

The key distinction is that HighLevel actually understands the concept of an agency paying for client usage and then rebilling the sub-account. Its current documentation explicitly describes SMS/email usage, agency wallets, client wallets, Stripe billing, and markup. help.gohighlevel.com

If you tell me what you're currently using for email/SMS (e.g. Mailgun, SendGrid, Twilio, Brevo, Klaviyo, etc.) and roughly how many clients you have, I can narrow this down to the 2–3 platforms that make the most financial sense, including how the actual billing flow would work.

If your goal is “one agency account, multiple clients, and automatically charge clients for email sends, SMS usage, and our own services”, there are a few materially different approaches.

Best fit: HighLevel

HighLevel

HighLevel is probably the closest match to what you're describing. Its agency/sub-account model is specifically built around this.

• Central agency wallet for usage-based costs.
• Client sub-accounts can consume SMS, email, phone/AI and other usage-based services.
• You can enable rebilling, so the agency pays the wholesale cost and charges the client with a markup. help.gohighlevel.com
• Email rebilling allows an agency to automatically mark up email-related costs. help.gohighlevel.com
• You can also sell fixed-price services/subscriptions separately through the SaaS/reselling functionality. help.gohighlevel.comwww.twilio.com
• This makes it possible to have something like $499/month + SMS usage + email usage + additional managed services on the same client relationship.

If you're primarily a marketing/automation agency, I'd start here.

Best for a broader white-label agency/reseller operation: Vendasta

Vendasta

Vendasta is stronger if you're selling a catalog of services rather than primarily running campaigns/automation yourself.

It supports:

• recurring client subscriptions
• one-time charges
• custom services
• automated invoices
• white-label client experience
• wholesale vs. retail pricing
• consolidated client billing. www.vendasta.com

It also has built-in email/SMS campaigns, with usage counters for marketing email and SMS. docs.vendasta.com

The distinction I'd make is:

HighLevel = agency operating system + usage rebilling

Vendasta = agency marketplace/reseller + billing

More flexible but more DIY: Twilio + your own billing layer

Twilio

Twilio gives you very strong infrastructure if SMS is the core product. You can create subaccounts for individual customers and have all their usage roll up to your main account. www.twilio.com

It also supports consolidated billing and programmatic usage data. www.twilio.com

The catch: Twilio isn't really an agency billing application. You'd generally need Stripe/another billing system plus your own logic to turn:

Client A → 2,431 SMS → $X
Client A → 18,400 emails → $Y
Client A → monthly management → $Z

into a client invoice.

My recommendation

If you're trying to build an agency model where the client sees one bill from you, I'd rank them:

I'd choose HighLevel if your clients are using the platform itself. Its wallet/rebilling architecture is unusually close to the model you described: the agency maintains the underlying infrastructure, usage gets attributed to subaccounts, and you can recover the wholesale cost plus markup. help.gohighlevel.com

If, however, you're already using another email/SMS platform and mainly need a system that aggregates all of those usage charges plus your service fees into a single client invoice, that's a different shortlist. In that case, I can compare HighLevel vs Vendasta vs Stripe Billing + usage metering vs AgencyAnalytics/other agency billing tools specifically for that architecture.

Yes. If you mean an agency platform where you can centrally manage clients and charge them for email sends, SMS usage/credits, plus your own services, the strongest options are:

1. HighLevel — probably the closest match

HighLevel is particularly designed around this model.

Its Agency Wallet centrally pays for usage such as SMS/phone, email, AI and other usage-based services. You can then enable rebilling so the corresponding usage is charged to the client/sub-account, either at cost or with an agency markup. help.gohighlevel.com

For example, you could structure a client as:

• $499/month — marketing services
• $50/month — platform/software
• Email: $X per 1,000 sends
• SMS: $X per message/credit
• AI usage: marked up
• Additional services: SEO, websites, ads, etc.

The important part is that the agency controls the billing relationship, rather than making every client maintain separate Twilio/Mailgun/etc. accounts.

HighLevel currently supports email rebilling and phone/SMS rebilling, with markup capabilities depending on the agency plan. Its current documentation says markup-enabled rebilling is available on the $497 Agency Pro tier for supported services. help.gohighlevel.comdocs.vendasta.com

I'd choose HighLevel if your main objective is:

"One agency account → lots of client accounts → automatically meter communications → bill clients for usage → add our margin."

2. Vendasta — better if you're selling a broader service catalog

Vendasta takes a more agency commerce/reseller approach.

It lets you create products/services, establish wholesale versus retail subscriptions, and centrally invoice clients. Each client can have multiple subscriptions, and you can consolidate renewals into a single monthly invoice. www.vendasta.com

Vendasta also has email/SMS campaign functionality with usage counters, although its model is more oriented toward plans/add-ons and products than HighLevel's granular communications rebilling. docs.vendasta.com

I'd lean toward Vendasta if your agency sells things like:

SEO + website + reputation management + ads + social + email/SMS + reporting + other SaaS products

and you want the commerce/catalog/invoicing layer to be a major part of the platform.

3. Twilio + Stripe — best if you want to build your own system

If you're actually building a SaaS/agency platform rather than adopting an agency CRM, Twilio + Stripe gives you the most control.

You can meter:

• SMS segments
• phone minutes
• email sends
• WhatsApp messages
• AI usage
• storage
• API calls
• virtually anything else

and turn those measurements into client invoices/subscriptions.

But unlike HighLevel, you have to build the agency hierarchy, usage ledger, credit system, markup logic, invoicing, dashboards, etc. yourself.

My recommendation

For your specific wording — "bill clients for sends, SMS credits and services centrally" — I'd investigate them in this order:

🥇 HighLevel → best out-of-the-box agency usage rebilling
🥈 Vendasta → best if you're essentially running an agency marketplace/service catalog
🥉 Twilio + Stripe → best if this is a custom SaaS product and you want complete control

One important distinction: if by "credits" you mean you want clients to pre-purchase, say, 10,000 email credits + 1,000 SMS credits, have those credits decrement with usage, automatically recharge when low, and then also combine that with fixed service fees, HighLevel's wallet/rebilling model is especially relevant. Its wallet system supports preloaded balances and auto-recharge for usage-based services. help.gohighlevel.com

If you tell me whether you're looking for (a) an agency CRM you can use internally, (b) a white-label platform you resell to clients, or (c) the billing infrastructure for a software product you're building, I can narrow this down to the best 3–5 options and compare their actual billing mechanics.

If your goal is one agency account that pays the underlying costs, then centrally bills each client for SMS, email sends/credits, and your own services, there are a few good options—but HighLevel is probably the closest match.

1. HighLevel — my first choice

HighLevel is unusually well suited to this model.

Its Agency Wallet lets you centrally fund usage, while client sub-accounts can be rebilled for the usage they generate. Current HighLevel documentation specifically covers:

• SMS/phone usage
• Email usage
• AI usage
• Workflow/premium-feature usage
• Other resold services
• Agency-defined markups
• Client wallets/credits
• Stripe-based client collection
• White-labeled client invoices

The $297 plan supports rebilling at cost for supported services; the $497 Agency Pro plan adds markup-based rebilling/SaaS Mode. help.gohighlevel.com

The important distinction is that HighLevel can handle both:

Usage

Client A → 10,000 SMS → agency gets charged wholesale → Client A gets charged your retail rate

Services

Client A → CRM + reputation management + website + SEO → $799/mo

So you can combine those into a single client relationship rather than maintaining separate billing systems. HighLevel also supports reselling additional services such as listings, SEO, domains, WhatsApp, WordPress hosting, etc. help.gohighlevel.com

For email specifically, HighLevel now supports email rebilling, including agency markup on the appropriate plans. help.gohighlevel.com

This would be my pick if you're building a marketing agency/SaaS model.

2. SlickText — excellent if SMS is the core product

SlickText has particularly good agency functionality around SMS credits.

You can consolidate billing under the agency account, allocate message credits across multiple client brands, monitor usage, and establish auto-refill rules. It also supports directly billing individual customers if that's preferable. www.slicktext.com

The catch: it's primarily an SMS platform, so it's not as good as HighLevel for combining SMS/email usage with CRM, automation, websites, SEO, managed services, etc.

3. Vendasta — best for a broad agency service catalog

Vendasta is compelling if what you really want is:

Agency → one billing relationship → lots of products/services → different pricing per client

Vendasta provides centralized invoicing, recurring billing, service catalogs, Stripe payments, one-time charges, setup fees, and reselling of marketplace products. www.vendasta.comhelp.gohighlevel.com

I'd choose Vendasta over HighLevel if your agency is more of a managed-service/product reseller and less of a CRM/SMS automation company.

The weakness for your particular use case is that it's not as elegantly centered around metered communication usage as HighLevel.

4. XUNA — interesting for AI + SMS agencies

XUNA AI is worth looking at if your "sends" are increasingly AI voice/SMS/chat consumption.

It explicitly supports wholesale credits, client-level usage, agency markup, and billing models based on usage, retainers, or hybrids. It also provides sub-accounts and white-labeling. www.xuna.ai

So a model like:

$299 platform fee + $0.XX/SMS + $X/minute voice + $X/chat

is very much what it's designed around.

5. Gestmi — more agency-management oriented

Gestmi is interesting if you want the billing + client portal + project/service management side more than a marketing automation platform.

It supports client-specific communication allowances and charges usage above those allowances for email, SMS and WhatsApp. help.gohighlevel.comhelp.gohighlevel.comgestmi.com

I'd consider it if your agency sells substantial human-delivered services alongside communications.

What I'd shortlist

For your exact requirement, I'd rank them:

🥇 HighLevel — best combination of SMS + email + usage rebilling + services + client accounts + white-label SaaS.

🥈 Vendasta — best if the emphasis is on selling lots of different agency services/products and having centralized commerce/billing.

🥉 SlickText — best if SMS credits are the central thing you're reselling.

4. XUNA — particularly interesting for an AI/voice/SMS business.

5. Gestmi — good if you're primarily looking for an agency operating system with metered communications layered into client billing.

One important distinction: if by "centrally" you mean the client should receive one monthly invoice from your agency containing their retainer + SMS + email + setup/management services, rather than separate usage charges/wallet transactions, I'd narrow the field further. HighLevel can get you there, but Vendasta or a dedicated agency billing layer may give you a cleaner invoice-centric model. www.vendasta.comhelp.gohighlevel.com

If you tell me what you're selling (e.g. email marketing, SMS marketing, lead gen, websites, SEO, AI agents) and roughly how many clients, I can give you a more specific HighLevel vs Vendasta vs a custom Stripe setup recommendation.

If your goal is “one agency account pays the wholesale costs, then we centrally charge each client for email sends, SMS credits, and other services—with markup”, there are a few strong options, but HighLevel is probably the closest fit.

1. HighLevel — best overall fit

This is the one I'd investigate first.

HighLevel has an Agency Wallet where your agency funds usage-based services, including email and phone/SMS. You can then enable rebilling so the client's sub-account is charged for its usage, including your markup. It also supports reselling additional services. help.gohighlevel.com

For example, you could structure a client like:

• Software/platform: $199/mo
• Email: $0.001/email or whatever retail rate you choose
• SMS: $0.03/message
• Phone numbers: $5/mo
• AI usage: cost + markup
• Review management: $99/mo
• SEO: $299/mo
• One-off agency services: $500

The important part is that the agency can be the central billing layer, rather than making you separately invoice every usage charge.

HighLevel currently supports email and phone/text rebilling, with the more advanced rebilling capabilities on its higher agency plans. Its current documentation says the $497 Agency Pro plan includes Email/Phone/Text Rebilling, while the $297 plan has more limited rebilling capabilities. help.gohighlevel.com

HighLevel pricing and billing documentation

2. Vendasta — best if you want a broader agency marketplace

Vendasta is particularly interesting if you're selling lots of different services, rather than primarily communications.

It has a product catalog, subscriptions, recurring billing, one-time invoices, Stripe Connect payments, client-facing marketplace, and white-label functionality. www.vendasta.com

Its Campaigns product also handles email and SMS, with usage counters for the client's monthly allocation. docs.vendasta.com

I'd think of Vendasta as:

“Agency storefront + service catalog + billing platform”

whereas HighLevel is more:

“CRM/marketing platform + communications infrastructure + agency rebilling.”

Vendasta Merchant Services

3. Stripe + Twilio/Mailgun/etc. — best if you want maximum control

If you're building your own agency platform, you can create a much more sophisticated model using Stripe Billing as the central billing engine and meter:

• Email sends
• SMS segments
• Phone minutes
• AI tokens
• Leads
• Ad spend
• Storage
• App seats
• Client-specific services

This gives you the most control over your pricing model, but you have to build the metering, usage synchronization, invoices, client portal, failed-payment handling, etc. yourself.

My recommendation

If you're asking because you're trying to choose software for an agency, I'd narrow it down to:

HighLevel → best if email/SMS/CRM/automation are core to what you're reselling.

Vendasta → best if you're effectively building a white-label agency services marketplace with lots of different products/services.

Stripe + custom integrations → best if your billing model is unusual and you need complete control.

For the specific requirement you gave—“bill clients for sends + SMS credits + services centrally”—I'd put HighLevel first. Its wallet/rebilling architecture is unusually close to exactly what you're describing. help.gohighlevel.com

If you tell me what software you're currently using for email/SMS (e.g. GoHighLevel, Mailchimp, Klaviyo, Twilio, Mailgun, etc.), I can compare the 3–5 best alternatives specifically for your stack and show how the client billing would work end-to-end.

If your goal is “one agency account pays the vendors, while each client gets charged for their own email sends, SMS usage/credits, and our service fees”, there are a few options—but HighLevel is the strongest fit by a fairly wide margin.

1. HighLevel — probably what you're looking for

HighLevel

HighLevel's model is almost exactly what you described:

• Agency Wallet: your agency centrally funds usage.
• Client/sub-account wallets: usage can be charged back to individual clients.
• SMS/phone usage: rebill the client's actual consumption.
• Email: rebill email usage.
• Markup: on the Pro/SaaS setup, you can charge clients above your wholesale cost and keep the margin.
• SaaS subscriptions: charge clients a recurring platform fee.
• Your own services: you can package your agency services alongside the software subscription.
• Stripe: handles the client-side payments.
• White label: clients can experience it as your own software. help.gohighlevel.com

The particularly useful piece is that HighLevel distinguishes usage-based rebilling from reselling fixed-price services. SMS, email, phone and other usage can flow through wallets and be rebilled, while things such as subscriptions/products can be sold as packaged services. help.gohighlevel.com

For example, you could theoretically structure a client like:

Marketing Platform — $299/mo
Managed Marketing Services — $1,000/mo
SMS usage — $0.XX/message
Email usage — $X/1,000 emails
AI usage — metered
Additional services — as needed

And have the client pay you rather than separately managing multiple Twilio/email/vendor invoices.

Important: the ability to add your own markup to usage is tied to the higher-tier Agency Pro/SaaS functionality. HighLevel currently lists the Agency Pro plan at $497/month, with Email/Phone/Text Rebilling and SaaS Mode. help.gohighlevel.com

2. Vendasta — better if you're selling lots of different services

Vendasta

Vendasta is compelling if your agency isn't primarily selling a CRM/marketing automation platform, but instead wants a white-label marketplace of digital services.

Its billing system lets you create packages, recurring invoices, one-time fees, setup fees, taxes, etc., and collect everything from one place. It also integrates products/services into the billing process. www.vendasta.com

The distinction I'd make is:

HighLevel: “I want to meter communications usage and build my agency's software/service business around it.”

Vendasta: “I want to sell 20 different digital services/products to clients and consolidate the commercial relationship.”

For your specific sends + SMS credits + agency services requirement, I'd favor HighLevel.

3. BotPenguin — interesting for a messaging-heavy model

BotPenguin

BotPenguin has a more explicit credit-based white-label approach for SMS/messaging. Partners can set client pricing above platform costs, retain the margin, and combine messaging with other services. It also supports Stripe and other payment gateways. botpenguin.comhelp.gohighlevel.com

I'd look at this if your product is essentially “messaging/AI communications as a service”, rather than a full CRM/marketing operating system.

My recommendation

If you're building an agency model where you want:

Agency → central vendor account → multiple clients → client-specific usage → automatic client billing → markup → recurring service fees

I'd shortlist them this way:

🥇 HighLevel — best for SMS/email metering + CRM + automation + SaaS + agency services.

🥈 Vendasta — best for a broader white-label digital-services marketplace.

🥉 BotPenguin — worth investigating if SMS/AI messaging is the core product.

One important distinction: “bill clients for sends” can mean two different things—either actual metered usage (e.g. 4,327 emails × your rate) or prepaid credit packs (e.g. 10,000 SMS credits). HighLevel is particularly strong at the former; platforms like BotPenguin lean more toward the latter. botpenguin.comhelp.gohighlevel.com

If you tell me what you're currently using for email/SMS (Twilio, Mailgun, SendGrid, HighLevel, etc.) and whether you want one invoice per client, I can narrow this down to the 3 best architectures and show how the money/credits flow between you, the vendor, and each client.

If you mean agency software where you pay the platform centrally, then charge each client for their actual email sends, SMS usage/credits, and your own services, there are two standouts:

1. HighLevel — probably the closest match

HighLevel pricing

This is the one I'd investigate first if usage-based billing is the core requirement.

HighLevel has an Agency Wallet that your agency funds centrally. Client/sub-account usage can then be rebilled to the client. This specifically covers things such as SMS/phone usage and email usage, and the agency can add a markup on supported services. help.gohighlevel.com

The current tiers are particularly relevant:

• $297/mo Unlimited: unlimited sub-accounts and rebilling of phone/email without markup.
• $497/mo Agency Pro: adds SaaS Mode and allows phone/email rebilling with markup. help.gohighlevel.comwww.gohighlevel.com

For example, you could conceptually have:

Client A
$499/month marketing service

• $25 SMS credits
• $8 email usage
• $50 one-time setup

→ all billed through your agency

And HighLevel handles the underlying usage accounting/rebilling rather than you having to reconcile Twilio/email-provider invoices manually. Its current documentation explicitly describes the agency wallet → client rebilling workflow. help.gohighlevel.com

Best fit: agencies that actually want clients using the same CRM/marketing platform and want to monetize usage.

2. Vendasta — better if you want an agency commerce/billing layer

Vendasta Platform

Vendasta approaches the problem differently. It's more of an agency marketplace + client management + billing/commerce platform.

It lets you create your own products/services, sell third-party products alongside them, and use centralized billing. You can have recurring charges, one-time charges, setup fees, taxes, etc. www.vendasta.com

Its subscription system tracks wholesale vs. retail pricing, meaning you can essentially define your cost and what the client pays. docs.vendasta.com

That's particularly attractive if your agency sells a mixture like:

• Email marketing
• SMS
• SEO
• Website management
• Paid advertising
• Social media
• Reputation management
• Consulting/managed services
• Third-party SaaS products

Vendasta is much more compelling than HighLevel if your primary goal is "one bill for everything the client buys from our agency." It explicitly positions itself around marketing, selling, billing and fulfilling services from one platform. www.vendasta.com

My recommendation

If your main requirement is:

"We need to buy SMS/email capacity centrally and automatically charge individual clients based on usage."

→ HighLevel is the stronger choice.

If your requirement is:

"We want a central agency commerce system where we can sell software + SMS/email + recurring services + one-off services and put everything on one client invoice."

→ Vendasta is worth looking at first.

There's also an important distinction: HighLevel is much more usage/rebilling-native, whereas Vendasta is stronger as a general agency product catalog + billing/commerce system.

If you tell me what you're currently using for email/SMS (e.g. Twilio, Mailgun, SendGrid, Amazon SES, etc.) and roughly how many clients you have, I can narrow this down to the 3–5 platforms that actually fit your billing model and compare their markup, wallets/credits, Stripe billing, client invoices, and API capabilities.