ChatGPT answers, unedited

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.