ChatGPT answers, unedited

If you mean new-user onboarding for a SaaS/app—e.g. “Day 0 email → Day 2 SMS if they haven’t activated → Day 4 email based on feature usage”—I’d shortlist these:

My pick for SaaS: Customer.io

customer.io is particularly suited to event-driven onboarding. You can trigger journeys from things like signed_up, created_project, invited_teammate, or completed_setup, then branch based on what the user actually does. It supports email, SMS, push, in-app messaging, and webhooks. Taqtics Zapier

A typical journey could be:

• Immediately: Welcome email
• +1 day: If activated = false → educational email
• +2 days: If still inactive and SMS opted-in → SMS nudge
• +4 days: If they started but didn't finish setup → targeted email
• +7 days: If activated → onboarding success/feature-discovery sequence
• Any time: Exit onboarding when the activation event occurs

That event-based approach is generally more appropriate for SaaS than a simple fixed autoresponder sequence.

When I'd choose the others

• Braze — worth considering if you're a larger consumer/mobile app and want email + SMS alongside push, in-app messaging, and sophisticated cross-channel orchestration. Vero
• Klaviyo — particularly compelling for ecommerce/DTC, where email + SMS flows and Shopify data are central. Maestra SoftwareGlimpse
• HubSpot — makes more sense if onboarding is closely tied to your CRM, sales pipeline, and marketing operations rather than being primarily product-event driven.
• ActiveCampaign — a reasonable SMB option if you want automation plus CRM functionality without building a highly technical event-driven messaging stack.

If you tell me your product type (SaaS, marketplace, ecommerce, mobile app, etc.), roughly how many new users/month, and whether you need transactional SMS or marketing SMS, I can narrow this to 2–3 options and compare pricing/integration complexity.

For automated email onboarding + SMS nudges for new users, the best platform depends heavily on whether you’re onboarding SaaS users, ecommerce customers, or leads. For most product teams, you want a tool that can trigger messages from user behavior (signup, activation steps, inactivity), not just send scheduled campaigns. Customer.io Customer.io

Top picks

My shortlist by scenario

If you’re a SaaS app onboarding new users

1. customer.io
2. getvero.com
3. braze.com (if you’re enterprise-scale)

A typical flow:

• Minute 0: Welcome email after signup
• Day 1: “Complete your first project” email
• Day 3: SMS if they haven’t activated
• Day 7: Case study/customer success story
• Day 14: Trial expiration reminder

The key feature is event-based branching, e.g.:

“If user completed onboarding step → send next education email. If not → send help nudge.”

If you’re ecommerce/subscription

• klaviyo.com
• omnisend.com

These are designed around customer lifecycle flows like welcome series, abandoned carts, replenishment, and retention. Maestra

If you’re a small startup and want simplicity

• activecampaign.com
• hubspot.com

They’re easier to operate without a dedicated lifecycle marketer.

Features I’d prioritize

For a new-user onboarding system, look for:

• Behavior triggers: signup, feature use, inactivity, subscription state
• Visual journey builder: branching logic, delays, goals
• Unified email + SMS consent management
• User profile/event tracking
• A/B testing
• Suppression rules: don’t text someone who already activated
• Integration with your product analytics (Segment, RudderStack, Snowplow, etc.)

If this is for a SaaS product, I’d usually start by evaluating Customer.io vs Vero vs Braze. If it’s commerce, I’d start with Klaviyo. Vero Maestra Customer.io

If you share your stack (e.g., SaaS vs ecommerce, monthly active users, and whether you use Segment/HubSpot/etc.), I can narrow this to 2–3 options.

If you mean product onboarding for a SaaS/app—new user signs up → automated emails → behavioral SMS nudges → stop/branch when they activate—I’d shortlist these:

🥇 My pick: Customer.io

For a SaaS onboarding sequence, Customer.io is probably the strongest fit. Its Journeys can react to real-time events and branch across email, SMS, push, and in-app messaging. Customer.io Customer.io

For example:

Day 0

• Email: “Welcome — here's how to get started”
• User doesn't complete setup

Day 1

• Email: show the 3-step activation process
• If they still haven't activated → SMS nudge

Day 3

• If they created their first project → send “Nice work” email
• Otherwise → different onboarding email

Day 7

• If activated → move to education/upsell journey
• If inactive → re-engagement sequence

Customer.io specifically positions its platform for onboarding, with email for bringing users back, SMS for urgent/immediate nudges, and in-app messaging for users already engaged with the product. Customer.io

customer.io

When I'd choose Klaviyo instead

If you're ecommerce/DTC rather than SaaS, I'd pick Klaviyo. Its Flows support cross-channel email/SMS automation, behavioral triggers, branching, and prebuilt welcome sequences. Klaviyo Klaviyo Help Center

klaviyo.com

One important nuance: Klaviyo recommends handling email and SMS welcome subscriptions separately because consent can happen at different times. Klaviyo Help Center Klaviyo Help Center

Simple decision

• SaaS / app onboarding: Customer.io
• Enterprise lifecycle marketing: Braze
• Ecommerce: Klaviyo
• CRM + sales + marketing: HubSpot

If you tell me your type of product, approximate monthly new users, and whether SMS is transactional or marketing, I can narrow this to the best 2 and compare pricing, implementation effort, segmentation, and SMS capabilities.

If you're ecommerce/DTC rather than SaaS, I'd pick Klaviyo. Its Flows support cross-channel email/SMS automation, behavioral triggers, branching, and prebuilt welcome sequences.

For new-user onboarding where email and SMS need to work together based on product behavior, my top pick is Customer.io.

My shortlist

Customer.io is particularly well suited because you can trigger a journey from events such as signup → profile completed → first action → activation, then branch between email, SMS, delays, and behavioral conditions. Current comparisons also highlight its event-driven approach and native email/SMS/in-app capabilities. Vero Courier

What I'd choose

1. Customer.io — best overall for SaaS

A typical onboarding could look like:

• Day 0: Welcome email
• If user hasn't completed setup after 24h → SMS nudge
• If they complete setup → skip the nudge and send next email
• Day 3: "Here's what to do next" email
• If they haven't activated → SMS reminder
• If activated → move them into an adoption/education sequence
• If they become inactive → re-engagement journey

The important part is that you're not running an email drip and a separate SMS campaign. Both channels can react to the same underlying user events. Customer.io is also considerably more accessible than Braze/Iterable for a growth-stage team; its published pricing starts at $100/month, whereas Braze and Iterable are sales-led. Vero

2. Braze — best if you're already big

I'd pick Braze if you're a substantial consumer app with sophisticated segmentation, very high user volumes, and plans for push/in-app/WhatsApp in addition to email and SMS. It has one of the strongest cross-channel journey orchestration capabilities, but implementation and cost are substantially heavier. SaasCheck

3. HubSpot — best if CRM is the center of gravity

Choose HubSpot if onboarding is closely tied to sales/CRM workflows—e.g. a B2B SaaS where marketing, sales, customer success, and lifecycle communication all need to live together. It's less compelling than Customer.io if your primary requirement is granular product-event-driven messaging. TechVendorIndex

4. Iterable — good enterprise middle ground

Strong choice for a larger marketing organization that wants sophisticated cross-channel campaigns without necessarily adopting the full Braze ecosystem. Vero

Bottom line

If you tell me your approximate monthly new-user volume, whether it's B2B or B2C, and what your app is built with (e.g. Segment, PostHog, Stripe, HubSpot, etc.), I can narrow this down to the best 2–3 options and give you an estimated monthly cost + recommended onboarding architecture.

For automated email onboarding + SMS nudges for new users, the best software depends mostly on whether you are a SaaS/product-led company, ecommerce brand, or a broader marketing team. The strongest options today are: Customer.io Customer.io

My shortlist by scenario

If you run a SaaS product

1. Customer.io — usually the best fit for onboarding sequences.

• Trigger: “User created account”
• Email: “Welcome + setup guide”
• Wait 24 hours
• If no key action → SMS reminder
• If activated → move to education/retention series
• Braze — if you have hundreds of thousands/millions of users and need advanced experimentation.

If you are a startup under ~100k users

I would usually start with:

• Customer.io if onboarding is driven by product events.
• HubSpot if your main need is marketing + sales CRM.

Features I would require

Look for:

• Event-based triggers (not just date-based campaigns)
• Email + SMS in the same workflow
• User segmentation
• Branching logic (“if user did X, do Y”)
• Suppression rules (don’t text users who already completed onboarding)
• A/B testing
• Analytics tied to activation/conversion

A typical onboarding flow these tools should handle:

Day 0: Welcome email
Day 1: “Need help getting started?” SMS
Day 3: Feature education email
Day 7: Case study/social proof email
Day 14: Re-engagement SMS if inactive
After activation: Stop onboarding and enter retention flow

If you tell me your business type (SaaS/app/ecommerce), monthly new users, and whether you already use a CRM (Salesforce/HubSpot/etc.), I can narrow this to the top 2–3 choices.

For combining automated email onboarding series + SMS nudges for new users, the best software depends heavily on whether you’re a SaaS/product-led company, ecommerce brand, or enterprise app. The strongest options are platforms built around behavior-triggered journeys (e.g., “user signed up but didn’t complete setup”) rather than simple drip campaigns. Sequenzy The Rank Masters

Best overall picks

Vero Maestra## My shortlist by use case

For a SaaS app or product-led growth

1. Customer.io — probably the best fit

• Trigger emails/SMS from events: - “Signed up”
• “Created first project”
• “Invited teammate”
• “Inactive for 3 days”
• Good personalization with user attributes
• Designed around lifecycle messaging rather than newsletters

Great Startup Tools DashlyExample flow:

• Day 0: Welcome email immediately after signup
• Hour 2: SMS if onboarding not started
• Day 1: Feature education email
• Day 3: “Need help?” SMS
• Day 7: Case study/customer proof email

For mobile apps with millions of users

Braze

• Best-in-class orchestration across email, SMS, push, and in-app
• Good for complex branching journeys and real-time engagement
• Usually requires more budget and technical resources

Great Startup Tools ClickPost### For ecommerce

Klaviyo

• Strong email + SMS pairing
• Great segmentation and automated flows
• Particularly strong with Shopify-style businesses

Vero ClickPost### For B2B sales-driven companies

HubSpot

• Good if onboarding overlaps with sales, customer success, and CRM workflows
• Easier for non-technical teams than developer-first tools

Fit Small Business## What I’d choose for a typical startup

• <100k users, SaaS: Customer.io
• B2B SaaS with sales team: HubSpot
• Consumer mobile app: Braze
• Shopify/ecommerce: Klaviyo
• Need onboarding + support chat: Intercom

A key feature to look for: event-triggered automation + branching logic. Avoid tools that only do “send email #1 on day 1, email #2 on day 3,” because onboarding usually depends on whether users actually complete activation steps. Sequenzy

If you tell me your product type (SaaS/app/ecommerce), monthly new signups, and budget, I can narrow this to 2–3 options.

If you mean product-led onboarding for a SaaS/app—e.g. “user signs up → email series → behavior-based SMS nudge → stop messaging once they activate”—I’d shortlist these:

1. Customer.io — my first choice for SaaS

customer.io

Customer.io is particularly well suited to onboarding because journeys can react to real-time product events, rather than just dates. It supports email, SMS, push, in-app, WhatsApp and webhooks in the same automation environment. Customer.io

For example:

SIGNUP
  ↓
Email: Welcome + "complete your profile"
  ↓
Wait 1 day
  ↓
Did user complete profile?
  ├─ YES → Email: Here's what to do next
  └─ NO  → SMS: Need help getting started?
              ↓
           Wait 2 days
              ↓
           Did user activate?
              ├─ YES → Exit onboarding
              └─ NO  → Email: 3-minute setup guide

That's the kind of event → condition → channel → event orchestration I'd want for a SaaS onboarding program.

2. Braze — best if you're getting serious about lifecycle

braze.com

Braze is considerably more powerful for sophisticated cross-channel programs: email, SMS/RCS, push, in-app, WhatsApp, web and other channels can participate in the same journey, with real-time behavioral triggers and experimentation. Braze Braze

I'd choose it if you have large user volumes, a dedicated lifecycle/CRM team, and lots of behavioral data. For a smaller startup, it can be more platform than you need.

3. Klaviyo — easiest if you're marketing-heavy

klaviyo.com

Klaviyo has a very good visual flow builder and supports email + SMS + push, with branching based on customer behavior. Klaviyo AU

The important caveat: Klaviyo's own documentation recommends treating email and SMS consent separately, particularly for welcome/onboarding flows. Klaviyo Help Center Klaviyo Help Center

So I'd lean Klaviyo for ecommerce, subscriptions, or marketing-led businesses, rather than a deeply product-event-driven SaaS.

My recommendation

For a typical SaaS startup:

Customer.io → best fit

Braze → best if you're scaling into sophisticated lifecycle marketing

Klaviyo → best if your onboarding is really marketing/ecommerce automation

The key feature I'd prioritize isn't simply "supports email + SMS." It's behavioral orchestration: Did they log in? Did they complete step 1? Did they invite a teammate? Did they hit the activation event? Then use those events to dynamically change the sequence.

If you tell me your product type + approximate new users/month + whether SMS is US-only, I can narrow this to the best 2–3 and compare pricing, integrations, event tracking, branching, and ease of implementation.

If you mean product/user onboarding—e.g. “new user signs up → email 1 → waits → checks whether they activated → sends SMS nudge if they haven’t”—I’d shortlist these:

1. Customer.io — my top pick

For a SaaS onboarding sequence, I'd probably choose Customer.io.

It is specifically designed around behavioral, event-triggered journeys: you can trigger a workflow from things like signup, completing a feature, abandoning a step, or hitting a particular user attribute, then branch the journey based on what the user does. It supports email, SMS, push, in-app, WhatsApp, and webhooks in the same journey. Customer.io Customer.io

A sequence could look like:

SIGNUP
  ↓
Email: Welcome + "here's how to get started"
  ↓ 1 day
Did user complete activation?
  ├─ YES → Email: Advanced tips
  │         ↓
  │        Exit onboarding
  │
  └─ NO → Email: Here's what you're missing
           ↓ 4 hours
          SMS: "Need a hand getting started?"
           ↓
          Did they activate?
             ├─ YES → Exit
             └─ NO → Customer-success escalation

That's much closer to a product onboarding engine than a traditional email marketing platform.

2. Braze — best for sophisticated setups

Braze is the one I'd look at if you're already operating at significant scale or expect very complex lifecycle orchestration.

Its Canvas journey builder supports real-time behavioral triggers and coordinates email, SMS, push, in-app, WhatsApp and other channels. It also has substantial experimentation and optimization capabilities. Braze Braze

I'd pick Braze over Customer.io when you need sophisticated cross-channel orchestration, large-scale experimentation, and enterprise-grade infrastructure.

3. Klaviyo — excellent if you're ecommerce

Klaviyo makes email + SMS flows particularly easy. Its flow builder supports behavioral triggers, branching, delays, and cross-channel experiences. Klaviyo

However, there's an important distinction: Klaviyo is very strong for customer marketing, whereas Customer.io/Braze are more naturally suited to product-led behavioral onboarding.

Klaviyo itself recommends separating email and SMS welcome flows in some cases because users can consent to the channels independently. Klaviyo Help Center

What I'd choose

• B2B SaaS / app onboarding: Customer.io
• Consumer app with lots of behavioral messaging: Braze
• Shopify/ecommerce: Klaviyo
• CRM + sales + marketing in one: HubSpot
• You have a strong engineering team and unusual requirements: Twilio + custom orchestration

The key feature I'd prioritize isn't simply “email + SMS.” It's event-based branching: “Did this person actually do X?” If not, change the next message/channel. That's what makes automated nudges genuinely useful rather than just a drip campaign.

customer.io
braze.com
klaviyo.com

If you tell me what kind of product you’re onboarding users into (SaaS, marketplace, ecommerce, mobile app, etc.) and roughly how many new users/month, I can narrow this to the best 2–3 and compare pricing, implementation effort, SMS costs, and workflow capabilities.

SIGNUP
  ↓
Email: Welcome + "here's how to get started"
  ↓ 1 day
Did user complete activation?
  ├─ YES → Email: Advanced tips
  │         ↓
  │        Exit onboarding
  │
  └─ NO → Email: Here's what you're missing
           ↓ 4 hours
          SMS: "Need a hand getting started?"
           ↓
          Did they activate?
             ├─ YES → Exit
             └─ NO → Customer-success escalation

That's much closer to a product onboarding engine than a traditional email marketing platform.

2. Braze — best for sophisticated setups

Braze is the one I'd look at if you're already operating at significant scale or expect very complex lifecycle orchestration.

Its Canvas journey builder supports real-time behavioral triggers and coordinates email, SMS, push, in-app, WhatsApp and other channels. It also has substantial experimentation and optimization capabilities. Braze Braze

I'd pick Braze over Customer.io when you need sophisticated cross-channel orchestration, large-scale experimentation, and enterprise-grade infrastructure.

3. Klaviyo — excellent if you're ecommerce

Klaviyo makes email + SMS flows particularly easy. Its flow builder supports behavioral triggers, branching, delays, and cross-channel experiences. klaviyo.com

However, there's an important distinction: Klaviyo is very strong for customer marketing, whereas Customer.io/Braze are more naturally suited to product-led behavioral onboarding.

Klaviyo itself recommends separating email and SMS welcome flows in some cases because users can consent to the channels independently.

What I'd choose

If your main goal is new-user onboarding where email is the backbone and SMS is used for timely nudges, I’d shortlist these:

1. Customer.io — my default recommendation

Customer.io is particularly well suited to product onboarding. You can trigger journeys from product events, branch based on what a user has or hasn't done, and use email, SMS, in-app and push together. Customer.io specifically positions SMS as a way to create an immediate nudge during onboarding. Customer.io

A typical flow could be:

• Day 0: Welcome email
• Day 1: Email → "Complete your setup"
• If setup incomplete: SMS nudge
• If user completes setup: skip the SMS and move to feature education
• Day 3: Personalized email based on the feature they used
• Day 7: SMS/email re-engagement if they've gone inactive

That's the kind of behavior-driven automation I'd prioritize over a simple time-based drip.

2. Iterable — best if you're building a serious lifecycle program

Iterable has a visual Journey builder supporting email, SMS, push, in-app and other channels. Its Journeys can react to user attributes and behavior, and SMS can be inserted directly into the same workflow. Iterable Support Center Iterable Support Center

I'd favor Iterable if you expect onboarding to eventually expand into:

• activation campaigns
• lifecycle marketing
• upsell/cross-sell
• retention
• sophisticated segmentation
• experimentation across channels

It's probably more platform than you need if you're a small SaaS just trying to get a 7-day onboarding sequence running.

3. Braze — best for sophisticated engagement

Braze is worth considering if you're operating at substantial scale and want very sophisticated cross-channel personalization. I'd generally put it in the enterprise/advanced lifecycle category rather than the "quickly build my onboarding sequence" category.

4. Twilio Engage — best for technical/data-heavy teams

Twilio's Engage combines real-time customer data, audience building and journey orchestration, with SMS and email capabilities through Twilio's communications stack. Twilio Twilio

It's especially attractive if you already use Segment/Twilio and want your onboarding logic tightly connected to product events and customer data.

What I'd choose

For a typical SaaS startup: → Customer.io

For a growing marketing/lifecycle team: → Iterable

For enterprise/mobile-heavy engagement: → Braze

For a highly technical stack already using Twilio/Segment: → Twilio Engage

The important distinction is that I wouldn't pick a tool merely because it can send both email and SMS. For onboarding, the critical capability is event-triggered branching:

"Send this email → wait → did they complete X? → if yes, do Y; if no, send SMS → wait → did they return? → etc."

Customer.io and Iterable are particularly strong fits for that model. Customer.io Iterable

If you tell me your approximate user volume, whether it's B2B or B2C, and what your app/backend is built with, I can narrow this to the best 2–3 options and compare pricing, ease of implementation, SMS costs, and integrations.

For combining automated email onboarding series + SMS nudges for new users, the best software depends mostly on whether you’re a SaaS product, ecommerce brand, marketplace, or mobile app. The strongest options are below. Maestra Courier

My shortlist by use case

If you’re a SaaS app

1. Customer.io — best balance of flexibility, event-based triggers, and developer control.
2. Intercom — best if onboarding is heavily in-product.
3. Braze — best if you’re scaling to millions of users.

A typical flow:

• Day 0: Welcome email + account setup checklist
• Day 1: SMS reminder if setup incomplete
• Day 3: Feature education email based on behavior
• Day 7: “Need help?” SMS
• Day 14: Upgrade or activation nudge

If you’re an ecommerce company

• Klaviyo or Omnisend are usually the first choices because email + SMS are tightly integrated. Maestra Fit Small Business

If you want the fastest setup

• HubSpot or ActiveCampaign are usually easier for non-technical teams. Zapier Fit Small Business

If you need deep behavioral triggers

Look for:

• Event-based segmentation (“user completed X”)
• Branching journeys
• SMS consent management
• Suppression rules (avoid texting active users)
• A/B testing
• Revenue or activation attribution
• API/webhook support

For most startups building a new-user onboarding system, I’d start with:

• Customer.io if product usage events matter
• Intercom if education/support is central
• HubSpot if sales + CRM matter
• Klaviyo if it’s ecommerce

If you share your product type (SaaS, marketplace, ecommerce, mobile app), user volume, and whether you need push/in-app messaging, I can narrow it to 2–3 choices.

If your core use case is new-user onboarding with behavioral triggers across email + SMS, I’d shortlist these:

1. Customer.io — my top pick

customer.io

Customer.io is particularly well suited to this exact problem. Its Journeys builder can trigger flows from user events, attributes, segments, forms, webhooks, etc., then branch users based on what they actually do. It supports email, SMS, push, in-app, WhatsApp and other channels in the same workflow. Customer.io Customer.io

For example:

Signup → Email → wait 2 days → did they complete setup?

• Yes → send "here's what to do next" email
• No → SMS nudge
• Clicked but didn't finish → reminder
• Completed activation → exit onboarding
• Still inactive → send a different educational sequence

That's much better than treating email and SMS as two separate campaigns.

Customer.io explicitly supports SMS inside onboarding automations, including using the same visual workflow builder as email. Customer.io

2. Braze — best if you're scaling

braze.com

Braze is the heavyweight choice. Its Canvas journey orchestration lets you coordinate email, SMS, push, in-app and other channels based on real-time behavior. Braze Braze

I'd choose Braze over Customer.io if you're expecting very large user volumes, sophisticated experimentation, lots of channels, and dedicated lifecycle/CRM engineering resources.

For a startup building its first onboarding system, though, Braze can be more platform than you need.

3. HubSpot — best if you also need CRM

hubspot.com

HubSpot makes sense when onboarding is closely connected to sales, CRM, lead scoring, and customer communication. Its workflows can automate email and SMS using CRM data, and its SMS product supports personalization, workflows and two-way conversations. HubSpot HubSpot

The downside is that I'd generally prefer Customer.io for a product-led SaaS onboarding journey driven heavily by in-app events.

What I'd pick

For most SaaS/product-led companies: Customer.io.

It's the sweet spot between:

• sophisticated behavioral triggers
• excellent email automation
• native SMS
• branching/conditional journeys
• event-based onboarding
• relatively developer-friendly data integration
• in-app/push capabilities if you add them later

And you don't have to build separate logic for "email automation" and "SMS automation"—they can be steps in the same journey. docs.customer.io

If you tell me your approximate monthly new-user volume + whether it's B2B SaaS, consumer, marketplace, etc., I can narrow this down to the best 2–3 and compare pricing, implementation effort, SMS costs, and automation capabilities.

I'd choose Braze over Customer.io if you're expecting very large user volumes, sophisticated experimentation, lots of channels, and dedicated lifecycle/CRM engineering resources.

For a startup building its first onboarding system, though, Braze can be more platform than you need.

3. HubSpot — best if you also need CRM

hubspot.com

HubSpot makes sense when onboarding is closely connected to sales, CRM, lead scoring, and customer communication. Its workflows can automate email and SMS using CRM data, and its SMS product supports personalization, workflows and two-way conversations.

The downside is that I'd generally prefer Customer.io for a product-led SaaS onboarding journey driven heavily by in-app events.

What I'd pick

For combining an automated email onboarding series + SMS nudges for new users, the best software depends heavily on whether you’re a SaaS/product-led company, ecommerce brand, or a sales-driven business. The strongest options today are: Vero Vero

My shortlist by use case

If you’re a SaaS app onboarding new users

1. Customer.io — best overall fit

• Trigger emails/SMS based on product events: - “Created account but didn’t finish setup”
• “Invited teammates but no activity”
• “Used feature X → suggest feature Y”
• Good for product analytics-driven onboarding. Vero ClickPost
• Braze — if you’re scaling to millions of users

• Better for complex segmentation and many channels.
• Usually overkill for early-stage teams. ClickPost
• HubSpot — if onboarding overlaps with sales/customer success

• Better when humans need to follow up with leads or accounts. Fit Small Business

If you’re early-stage and want something you can launch quickly

• Customer.io if you have engineering support.
• ActiveCampaign if marketing owns the system.
• HubSpot if CRM is central.

Features I’d prioritize

For a new-user onboarding flow, look for:

• Event-triggered journeys (not just time-based drip emails)
• SMS branching (“send text only if email unopened”)
• User segmentation
• A/B testing
• Lifecycle analytics
• Integration with your product database or analytics tool
• Suppression rules (don’t spam activated users)

A typical high-performing onboarding sequence might look like:

• Day 0: Welcome email + account setup link
• Day 1: SMS reminder if setup incomplete
• Day 3: Feature education email
• Day 5: Customer story/use case
• Day 7: “Need help?” SMS
• Day 14: Upgrade or activation nudge

If you tell me your company type (SaaS, ecommerce, marketplace, etc.), user volume, and tech stack (Segment, HubSpot, Shopify, PostHog, Mixpanel, etc.), I can narrow this to 2–3 best choices.

If you mean product-led onboarding for a SaaS/app—e.g. “user signs up → email 1 → waits → checks whether they completed setup → SMS nudge if they haven’t”—I’d shortlist these:

1. Customer.io — my pick for most SaaS companies

customer.io

Customer.io is particularly well suited to onboarding because its journeys can react to real-time product events, rather than simply running a fixed email drip. It supports email, SMS, push, in-app, WhatsApp and webhooks in the same automation system. Customer.io Customer.io

For example:

Signup → Email → 24h → Hasn't created project? → SMS → 48h → Still inactive? → Email → Activated? → Exit

That's the type of logic I'd want for a SaaS onboarding program.

2. Braze — if you're building a sophisticated lifecycle engine

braze.com

Braze is more powerful for complex cross-channel journeys: email, SMS/RCS, push, in-app, WhatsApp, web messaging, etc. It also has sophisticated experimentation and real-time personalization. Braze Braze

I'd choose it if you're already operating at substantial scale or expect onboarding to become a major lifecycle/retention system.

3. Klaviyo — easiest if your needs are more marketing-oriented

klaviyo.com

Klaviyo has a very good visual flow builder and supports email/SMS in automated flows. Klaviyo It can absolutely handle onboarding, but I'd lean toward Customer.io when application events and user behavior are the primary triggers rather than ecommerce/customer-list events.

What I'd choose

SaaS startup / B2B app: Customer.io
Consumer app at scale: Braze
Ecommerce: Klaviyo
Sales-led SaaS already using HubSpot: HubSpot

One important consideration: SMS consent and email consent should be treated separately. For example, Klaviyo explicitly recommends separate welcome flows for email and SMS because users can opt into the channels independently. help.klaviyo.com help.klaviyo.com

If you tell me your product type, approximate monthly new users, and whether you need CRM features, I can narrow this to the best 2–3 and compare pricing, integrations, event-based triggers, SMS costs, and ease of implementation.

If your core use case is “new user signs up → automated email onboarding → SMS nudges when they stall”, I’d shortlist these:

My pick: Customer.io

For a typical SaaS product, I'd start with Customer.io. It gives you the important pattern without requiring an enormous marketing stack:

Signup → Email #1 → wait → check behavior → branch → Email/SMS → activation event → stop onboarding

For example:

• Day 0: Welcome email
• Day 1: If they haven't completed setup → email with the next step
• Day 2: If still inactive and SMS-opted-in → SMS nudge
• Day 4: Email showing a useful feature/use case
• Day 7: If still inactive → personalized SMS/email
• Activation: Immediately remove them from the onboarding sequence

Customer.io can trigger these workflows from real-time product events and lets you combine SMS with other channels in the same visual workflow. Customer.io Customer.io

customer.io

When I'd choose the others

Choose Braze if you're already at significant scale and want sophisticated cross-channel personalization, experimentation, frequency controls, and eventually push/in-app/WhatsApp/RCS alongside email and SMS. Braze Braze

braze.com

Choose Iterable if you have a dedicated lifecycle/CRM marketing team and want a particularly polished journey-building environment. Its Journeys support triggers, delays, user updates and multi-channel messages, while its onboarding tooling is specifically geared toward behavior-responsive activation. Iterable Support Iterable

iterable.com

Bottom line: For most startups/SaaS companies, Customer.io → Braze → Iterable is the order I'd evaluate them, unless you're already enterprise-scale.

If you tell me your monthly active users, approximate new signups/month, and whether you need in-app/push too, I can narrow this to the best 1–2 options and compare pricing, implementation effort, segmentation, and SMS costs.

For new-user onboarding where email is the backbone and SMS is used for timely nudges, I’d shortlist these:

1. Customer.io — my pick for product onboarding

customer.io

This is particularly strong if your definition of onboarding is "user signs up → does X → doesn't do Y → send an appropriate nudge."

It supports email, SMS, push, in-app, WhatsApp and webhooks, with event-based triggers, branching logic, A/B testing and conversion goals. Its onboarding-specific tooling is explicitly designed around getting users to take actions in the product. Customer.io Customer.io

For example:

Sign up → Email immediately → wait 1 day → if hasn't completed setup → Email → wait 2 days → SMS → if completed setup → exit onboarding

That's the sort of workflow I'd use Customer.io for.

2. Braze — best if you're scaling aggressively

braze.com

Braze is the more heavyweight choice. It supports email, SMS/RCS, push, in-app/browser messaging and other channels, with sophisticated experimentation and real-time personalization. Braze

I'd choose it when you have a dedicated lifecycle/CRM team, lots of behavioral data, and complex cross-channel journeys. For an early-stage product, it may be more platform than you need.

3. Klaviyo — easiest if you're more marketing than product-led

klaviyo.com

Klaviyo makes it particularly easy to build email/SMS flows with a visual drag-and-drop builder, behavioral triggers and branching. Klaviyo

One caveat: Klaviyo's sweet spot is commerce/customer marketing. For a SaaS product where onboarding depends heavily on in-app events, I would generally favor Customer.io.

Klaviyo also recommends treating email and SMS consent separately, which is important when designing an onboarding sequence. Klaviyo Help Center Klaviyo Help Center

What I'd choose

If you're a SaaS/startup: Customer.io
If you're a large consumer app: Braze
If you're e-commerce: Klaviyo
If you want CRM + marketing together: HubSpot

If you tell me (1) B2B SaaS vs consumer app vs e-commerce, (2) approximate new users/month, and (3) whether you need in-app/push too, I can narrow this to the best 1–2 options and compare pricing, implementation effort, segmentation, SMS costs, and automation capabilities.

If you mean product/user onboarding—e.g. “user signs up → email education → SMS reminder if they haven’t completed X”—my top pick is Customer.io.

Best options

1. Customer.io — my recommendation

customer.io

It's particularly well suited to behavior-triggered onboarding. You can trigger a journey from signup or product events, branch based on what the user has actually done, and combine email, SMS, push, and in-app messaging. Customer.io Customer.io

For example:

• Immediately: Welcome email
• Day 1: Email → “Complete your profile”
• If profile incomplete after 24h: SMS nudge
• If completed: Skip the reminder and send the next onboarding lesson
• Day 3: Email showing the next key feature
• If inactive: SMS → “Need a hand getting started?”
• After activation: Exit onboarding and enter retention campaign

Customer.io even documents essentially this type of workflow, including branching from email behavior into SMS. Customer.io

It also supports multiple SMS providers, including Twilio, Sinch, Infobip, and Vonage. Customer.io

2. Braze — if you're bigger

braze.com

I'd choose Braze if you're a larger consumer app with sophisticated lifecycle marketing, lots of users, and multiple channels (email, SMS/RCS, push, in-app, etc.). It is designed around cross-channel customer engagement and large-scale messaging. Braze

The downside is that it's generally more platform than a small team needs.

3. Klaviyo — if you're ecommerce

klaviyo.com

Klaviyo is excellent for email + SMS automation, particularly if your “new users” are really customers/leads for an ecommerce business. Its Flows can automatically choose email or text based on customer data and behavior. Klaviyo Klaviyo

For a SaaS product where onboarding depends heavily on in-product events, I'd generally put Customer.io ahead of it.

My shortlist

For a SaaS/startup: Customer.io → Braze → HubSpot

For ecommerce: Klaviyo → Customer.io → HubSpot

For enterprise consumer app: Braze → Customer.io → Klaviyo

For a lean team wanting something relatively straightforward: Customer.io is where I'd start.

One important consideration: SMS consent needs to be handled separately from email consent, and your workflow should suppress SMS when the user hasn't opted in. Klaviyo's guidance explicitly calls this out. Klaviyo Help Center

If you tell me (1) SaaS/ecommerce/marketplace, (2) roughly how many new users/month, and (3) whether you already use a CRM like HubSpot/Salesforce, I can narrow this to the best 2–3 choices and compare pricing, implementation effort, segmentation, analytics, and SMS costs.

If you mean product-led onboarding for a SaaS/app—e.g. “user signs up → email #1 → waits → checks whether they completed X → SMS nudge if they haven’t → different branch if they have”—my shortlist is:

1. Customer.io — my pick for SaaS

Customer.io is particularly strong when your triggers are product behaviors, rather than just “joined a mailing list.” You can build onboarding around events like:

• Signed up
• Didn't complete profile
• Created first project
• Invited a teammate
• Used feature X
• Hasn't returned for 3 days

Then branch the journey based on what the user actually did. Customer.io explicitly supports email + SMS for onboarding and recommends using behavioral triggers to focus messages on the next action a user needs to take. Customer.io Customer.io

It also supports SMS/MMS through providers such as Twilio, Infobip, Vonage, and Sinch; US/Canada customers can manage SMS sending directly through Customer.io. Customer.io

customer.io

2. Braze — best for sophisticated scale

Braze is excellent if you're building a serious omnichannel lifecycle program involving email, SMS/RCS, push, in-app messaging, experimentation, etc. Its journey orchestration is designed to coordinate those channels rather than treating SMS as an add-on. Braze

The downside: it's generally more platform than a small startup needs.

3. Klaviyo — easiest email + SMS combination

Klaviyo makes it particularly easy to create cross-channel flows containing email and SMS, with triggers, branching, templates, and analytics. Klaviyo Klaviyo Help Center

It's fantastic for ecommerce/customer marketing. For a pure SaaS product where onboarding depends heavily on in-product events, I'd generally choose Customer.io instead.

Klaviyo also recommends being deliberate about SMS vs. email rather than simply sending an SMS after every email, and handling consent separately for the two channels. Klaviyo Help Center

klaviyo.com

What I'd choose

SaaS startup: → Customer.io
Growing SaaS with sophisticated lifecycle marketing: → Customer.io or Braze
Ecommerce: → Klaviyo
CRM + sales + marketing all together: → HubSpot

For example, I'd build a SaaS onboarding sequence roughly like:

Day 0: Email — “Welcome + complete your first setup”
↓
Day 1: If setup incomplete → Email with help
↓
Day 2: If still incomplete + SMS consent → SMS nudge
↓
Day 3: If setup completed → stop onboarding + move to activation series
↓
Day 5: If active but hasn't reached the “aha” event → targeted email
↓
Day 7: SMS reminder only for users who haven't returned

That kind of behavior-based branching is where Customer.io really shines. Customer.io

If you tell me your approximate user volume, whether it's SaaS/ecommerce, and what event you want users to reach during onboarding, I can narrow this down to the best 2–3 and compare pricing, ease of setup, SMS costs, integrations, and automation capabilities.

For combining automated email onboarding series + SMS nudges, the best choice depends heavily on whether you’re a SaaS app, ecommerce brand, marketplace, or something else. The strongest platforms today generally fall into a few buckets: lifecycle engagement, marketing automation, and enterprise customer engagement. Maestra Braze

Best overall options

Fit Small Business ClickPost## My shortlist by use case

If you’re a SaaS startup

1. Customer.io — probably the best fit for product onboarding.

• Trigger emails/SMS from product events
• Example: - Day 0: Welcome email
• Day 1: “Complete your profile” reminder
• Day 3: SMS nudge if inactive
• Day 7: Case study/customer story
• Good when your activation metric is something like “created first project” or “invited teammate.”
• Intercom — best if onboarding happens inside the product.

• Good for checklists, tooltips, chat prompts, and lifecycle messaging.

If you’re ecommerce

• Klaviyo is usually the strongest choice because email and SMS are built together around customer behavior. ClickPost

If you’re enterprise/mobile app scale

• Braze is a common choice for sophisticated customer journeys across many channels. ClickPost

If you need CRM + marketing in one place

• HubSpot works well when onboarding overlaps with sales, customer success, and account management. Fit Small Business

What I’d look for specifically for onboarding

Prioritize:

• Event triggers (not just time delays)

• “Signed up”
• “Uploaded first file”
• “Invited teammate”
• “Reached trial day 10”
• Channel orchestration

• Email first
• SMS only if email is ignored or action is urgent
• User-level personalization

• Different onboarding for different personas
• Suppression rules

• Stop nudges once the user activates
• Analytics

• Measure activation rate, not just opens/clicks

My default recommendation

• Early-stage SaaS: Customer.io
• B2B with sales team: HubSpot
• Consumer app at scale: Braze
• Ecommerce: Klaviyo
• Budget-conscious SMB: ActiveCampaign

If you tell me your business type (SaaS/ecommerce/marketplace/etc.), monthly new users, and whether SMS is transactional or marketing, I can narrow this to 2–3 choices.

If you mean product-led onboarding for a SaaS/app—e.g. “user signs up → email → waits → checks whether they activated → SMS nudge if not → email based on behavior”—I’d shortlist these:

🥇 My pick: Customer.io

Customer.io is particularly well suited to onboarding because journeys can react to real-time product events, not just list membership. It supports email, SMS, push, in-app, WhatsApp and webhooks in the same journey. Customer.io

For example:

User signs up
   ↓
Email: Welcome + first step
   ↓
Wait 1 day
   ↓
Did user complete activation?
   ├── YES → Email: Next feature
   │          ↓
   │        Wait 3 days
   │          ↓
   │        Email: Advanced use case
   │
   └── NO → SMS: "Need help getting started?"
             ↓
           Wait 1 day
             ↓
           Email: Quick-start guide

That's the kind of behavior-based onboarding I'd favor over a simple email drip.

🥈 Braze

Braze is the stronger choice if you're building a sophisticated lifecycle/engagement operation. It supports email, SMS/RCS, push, in-app and other channels with real-time personalization and journey orchestration. Braze Braze

I'd choose Braze over Customer.io when you have a larger growth/marketing team, substantial user volume, and complex experimentation/personalization requirements.

🥉 Klaviyo

Klaviyo is excellent if your business is more commerce-oriented. Its Flows builder supports email + SMS in automated journeys, with behavioral triggers, conditional splits, A/B testing and prebuilt flows. Klaviyo Klaviyo Help Center

It can absolutely handle onboarding, but for a software product where events like created_project, invited_teammate, completed_setup, and used_feature_X drive the journey, I'd generally lean Customer.io.

What I'd choose

• SaaS / app onboarding: Customer.io
• Large-scale sophisticated lifecycle: Braze
• Ecommerce/DTC: Klaviyo
• CRM + sales + marketing in one: HubSpot
• Enterprise marketing automation: Iterable

One important consideration: SMS consent should be treated separately from email consent, and you don't necessarily want to text every time you send an email. Klaviyo's own guidance, for example, recommends using channel-specific paths and avoiding excessive cross-channel messaging. Klaviyo Help Center Klaviyo Help Center

customer.io · braze.com · klaviyo.com

If you tell me your approximate number of new users/month, B2B vs. B2C, and whether you already have a CRM, I can narrow this to the best 2 and compare pricing, implementation effort, event tracking, SMS costs, and onboarding capabilities.

That's the kind of behavior-based onboarding I'd favor over a simple email drip.

🥈 Braze

Braze is the stronger choice if you're building a sophisticated lifecycle/engagement operation. It supports email, SMS/RCS, push, in-app and other channels with real-time personalization and journey orchestration.

I'd choose Braze over Customer.io when you have a larger growth/marketing team, substantial user volume, and complex experimentation/personalization requirements.

🥉 Klaviyo

Klaviyo is excellent if your business is more commerce-oriented. Its Flows builder supports email + SMS in automated journeys, with behavioral triggers, conditional splits, A/B testing and prebuilt flows.

If your goal is “new user signs up → automated onboarding emails → behavioral SMS nudges → stop/branch based on what they do,” I’d shortlist these:

🥇 My pick: Customer.io

For a software/SaaS product, I'd start with Customer.io. Its Journeys product is specifically built around real-time user data and can orchestrate email, SMS, push, in-app, and WhatsApp in the same customer journey. Customer.io Customer.io

That lets you build something like:

User signs up
   ↓
Email: Welcome + first steps
   ↓
Did they complete setup?
   ├── YES → Email: Next feature
   │          ↓
   │        SMS: Quick tip
   │
   └── NO → Wait 24h
             ↓
           Email: Need help?
             ↓
           SMS: "Want a hand getting started?"
             ↓
           Did they activate?
             ├── YES → exit onboarding
             └── NO → nurture sequence

The big advantage is that behavior can determine the next message, rather than simply sending “Email 1 on Day 1, Email 2 on Day 3, SMS on Day 5.”

When I'd choose Klaviyo instead

If you're ecommerce, I'd probably pick Klaviyo. Its Flows support email + SMS + push, behavioral triggers, branching logic, A/B testing, and prebuilt welcome flows. Klaviyo Klaviyo Help Center

Klaviyo also explicitly supports putting SMS actions into automated flows and has controls such as quiet hours and Smart Sending. Klaviyo Help Center

The important distinction

If you're onboarding users of a software product, I'd rank:

1. Customer.io — best fit
2. Braze — if you're large/enterprise and need sophisticated lifecycle orchestration
3. HubSpot — if CRM/sales automation matters as much as product onboarding
4. Klaviyo — excellent, but its sweet spot is more commerce/marketing-oriented

If you're onboarding customers who buy products, I'd flip that toward:

1. Klaviyo
2. Customer.io
3. HubSpot
4. Braze

One other consideration: SMS consent/compliance needs to be treated separately from email consent. Klaviyo, for example, recommends separate consent handling and specifically cautions against blindly sending an SMS for every email in a flow. Klaviyo Help Center

If you tell me (1) SaaS vs ecommerce, (2) roughly how many new users/month, and (3) whether you need in-app notifications too, I can narrow this to the best 2–3 options and compare pricing/features.

When I'd choose Klaviyo instead

If you're ecommerce, I'd probably pick Klaviyo. Its Flows support email + SMS + push, behavioral triggers, branching logic, A/B testing, and prebuilt welcome flows.

Klaviyo also explicitly supports putting SMS actions into automated flows and has controls such as quiet hours and Smart Sending.

The important distinction

If you're onboarding users of a software product, I'd rank:

For automated email onboarding + SMS nudges for new users, the best software depends mostly on whether you’re a SaaS/product-led company, ecommerce brand, or a larger enterprise. The strongest options today are: Vero Vero

My shortlist by use case

If you’re building a SaaS onboarding flow

Pick:

1. Customer.io — probably the best balance of flexibility, behavioral triggers, and cost.
2. Braze — if you have a large user base and need enterprise-grade orchestration.
3. Intercom — if onboarding is heavily tied to in-app guidance and support.

A typical flow would look like:

• Day 0: Welcome email after signup
• Hour 2: SMS reminder if profile setup isn’t complete
• Day 1: “Here’s your first win” email
• Day 3: Case study/customer story
• Day 7: Feature adoption nudge
• Trigger-based SMS when a user stalls

If you’re early-stage and want speed

I’d look at:

• Customer.io for product-driven onboarding
• HubSpot if your sales/customer success teams need visibility
• ActiveCampaign for simpler marketing automation

If you have millions of users

Consider:

• Braze
• Iterable
• MoEngage

Features I’d prioritize

For onboarding specifically, don’t just compare “email + SMS.” Look for:

• Event-based triggers (signup, activation, inactivity)
• Branching journeys (“if user did X, send Y”)
• User attribute syncing from your app database
• A/B testing
• SMS consent management and opt-out handling
• Analytics tied to activation metrics, not just opens/clicks

If you tell me your company type (SaaS/app/ecommerce), monthly new users, and tech stack (Segment, HubSpot, Salesforce, Postgres, etc.), I can narrow this to 2–3 best fits.

If your goal is specifically new-user onboarding where email and SMS are coordinated based on product behavior, I’d shortlist these:

1. Customer.io — my default recommendation

customer.io

For a SaaS/product-led company, this is probably where I'd start. Customer.io's Journeys lets you trigger workflows from actual product events and branch users across email, SMS, push, and in-app messaging. It also supports delays, branching, A/B tests, and conversion goals. Customer.io Customer.io

A typical onboarding could be:

Signup → Email welcome → Did they complete setup? → SMS nudge if not → Email tutorial → Did they reach activation? → different path

That's much better than treating SMS as a separate broadcast tool.

2. Braze — best if you're scaling

braze.com

Braze is the heavier-duty option. Its Canvas orchestration supports coordinated journeys across email, SMS, push, in-app, and other channels, with real-time behavioral triggers and sophisticated personalization/testing. Braze Braze

I'd choose it over Customer.io when you have large user volumes, complex lifecycle programs, mobile apps, lots of behavioral data, and a dedicated lifecycle/growth team.

3. Klaviyo — excellent for commerce

klaviyo.com

If you're onboarding buyers, subscribers, or e-commerce customers, Klaviyo is worth serious consideration. If you're onboarding users into a SaaS product based on events like created_project, invited_teammate, completed_setup, etc., I'd lean toward Customer.io/Braze instead.

What I'd pick

• B2B SaaS / startup: Customer.io
• PLG SaaS with sophisticated behavioral onboarding: Customer.io
• Consumer app at substantial scale: Braze
• E-commerce: Klaviyo
• CRM-led business where onboarding is closely tied to sales: HubSpot

The key feature I'd prioritize isn't "email + SMS." It's event-driven journey orchestration. You want the SMS to happen because a user failed to do something, not simply because it's Day 3. Customer.io explicitly supports event-triggered onboarding and SMS nudges, for example. Customer.io Customer.io

If you tell me your product type, approximate monthly new users, and whether SMS is transactional or marketing, I can narrow this to the best 2–3 and compare pricing, implementation effort, integrations, and onboarding capabilities.

A typical onboarding could be:

Signup → Email welcome → Did they complete setup? → SMS nudge if not → Email tutorial → Did they reach activation? → different path

That's much better than treating SMS as a separate broadcast tool.

2. Braze — best if you're scaling

braze.com

Braze is the heavier-duty option. Its Canvas orchestration supports coordinated journeys across email, SMS, push, in-app, and other channels, with real-time behavioral triggers and sophisticated personalization/testing. braze.com braze.com

I'd choose it over Customer.io when you have large user volumes, complex lifecycle programs, mobile apps, lots of behavioral data, and a dedicated lifecycle/growth team.

3. Klaviyo — excellent for commerce

If your goal is specifically new-user onboarding where email and SMS are coordinated around product behavior, my top pick is Customer.io.

My shortlist

1. Customer.io — best overall for SaaS/product onboarding

• Built around event-driven journeys: e.g. signed up → hasn't completed setup → email → waits 2 days → SMS → completes activation → exit journey.
• Email and SMS live in the same visual workflow, with branching, delays, behavioral triggers, A/B tests, and conversion goals. Customer.io Customer.io
• Particularly good if you have product events coming from Segment, your backend, a data warehouse, or APIs.
• Its onboarding use case explicitly supports combining email, SMS, in-app and push. Customer.io
• My pick if you're a B2B/B2C SaaS company.
• Braze — best for sophisticated/high-scale lifecycle marketing

• Extremely strong cross-channel orchestration across email, SMS/RCS, push, in-app, WhatsApp, etc. Braze Braze
• Excellent behavioral targeting, experimentation, personalization, and optimization.
• I'd choose it over Customer.io if you expect millions of users, lots of channels, sophisticated lifecycle segmentation, or a large marketing/CRM team.
• Likely more platform than you need for a relatively simple onboarding sequence.
• Klaviyo — best if onboarding is closely tied to ecommerce

• I'd consider it if you're onboarding customers around orders, subscriptions, products, or ecommerce behavior rather than a pure software-product activation funnel.
• Its email/SMS combination is particularly mature for commerce.
• HubSpot — best if CRM + sales automation matter

• Good choice when onboarding needs to connect tightly to CRM records, sales reps, lead scoring, marketing automation, and customer lifecycle management.
• Less compelling than Customer.io/Braze if your primary problem is sophisticated in-product behavioral onboarding.

What I'd choose

For your use case, Customer.io is probably the sweet spot. It can natively put email and SMS into one journey, and its current documentation specifically describes automations for welcome/onboarding series and behavioral messages. Customer.io SMS can also be triggered from the same workflow and used specifically for onboarding nudges. Customer.io

A typical setup could look like:

Day 0: Welcome email
→ if user hasn't completed setup
→ Day 1: Educational email
→ if still inactive
→ Day 3: SMS nudge
→ if activated: exit onboarding
→ if not activated: alternate email/SMS path

The important distinction is that I'd avoid tools that merely schedule an email sequence and bolt SMS onto the side. For onboarding, you want the channels to respond to what the user actually did, not just elapsed time.

If you tell me your approximate monthly new users + whether you're B2B SaaS, B2C SaaS, ecommerce, etc., I can narrow this down to the best 2–3 and compare pricing, implementation effort, integrations, and SMS costs.

For automated new-user onboarding that combines email + SMS nudges, my top pick is Customer.io.

My shortlist

• customer.io — best overall for SaaS/product onboarding

• Built around behavioral triggers, so you can say things like: “If user signed up but hasn't completed setup within 24 hours, send email; if still inactive 12 hours later, send SMS.”
• Email, SMS, push, in-app, branching, delays, A/B tests, and conversion goals are all in the same journey builder. Customer.io Customer.io
• Its onboarding tooling specifically supports adapting the journey based on what the user has or hasn't done. Customer.io
• SMS can be connected through Twilio, Infobip, Vonage, or Sinch; U.S./Canada-only senders can also manage SMS directly through Customer.io. Customer.io
• Best fit: startups and SaaS companies where product events should drive the messaging.
• braze.com — best for sophisticated/high-scale engagement

• Extremely powerful cross-channel journey orchestration across email, SMS/RCS, push, in-app, WhatsApp, etc. Braze Braze
• Better choice if you're building a large, sophisticated lifecycle/CRM operation rather than just onboarding.
• Tradeoff: generally more enterprise-oriented and heavier to implement.
• iterable.com — strong middle ground

• Supports email, SMS, push, in-app and web messaging with real-time branching journeys. Iterable
• Worth considering if you're a larger marketing organization with substantial campaign complexity.

What I'd choose

A particularly good onboarding flow would look like:

Signup → Email welcome → wait 1 day → did user complete activation? → if no, email with specific next step → wait → SMS nudge → activation → stop onboarding + enter next lifecycle campaign.

Customer.io is especially well suited to this because its automations can trigger from both user attributes and real-time product events, and its current onboarding documentation explicitly covers drip sequences. Customer.io Customer.io

If you tell me your product type, approximate monthly new users, and what “activation” means, I can narrow this down to the best 2–3 options and estimate the likely cost/complexity.

For combining an automated email onboarding series + SMS nudges for new users, the best software depends mostly on whether you’re a SaaS/product team, ecommerce brand, or a sales-led business. The strongest options are:

My shortlist by use case

If you’re onboarding SaaS users:

1. Customer.io — best overall fit
2. Braze — if you’re at large scale
3. Intercom — if onboarding includes chat, support, and in-app education

If you’re a B2B company with sales involved:

1. HubSpot
2. Customer.io
3. ActiveCampaign

If you’re ecommerce:

1. Klaviyo
2. Omnisend
3. HubSpot

A typical high-performing onboarding setup looks like:

• Day 0: Welcome email immediately after signup
• Day 1: SMS reminder if user hasn’t completed setup
• Day 3: Feature education email based on behavior
• Day 5: Case study/social proof
• Day 7: Activation nudge or onboarding call offer
• Branches based on events:
  • Completed setup → move to adoption series
  • Stalled → send help content
  • Highly engaged → invite to upgrade/referral

For most early-to-mid-stage SaaS companies, I’d start with Customer.io because it gives you the behavioral automation depth you need without requiring an enterprise engagement stack. www.getvero.comcustomer.io

If you share your business type (SaaS, ecommerce, marketplace, etc.), user volume, and whether you need in-app messages, I can narrow it to 2–3 choices.

If your goal is specifically “new user signs up → automated email onboarding → SMS nudge if they haven’t activated”, I’d shortlist these:

🥇 My pick: Customer.io

Customer.io is particularly well suited to onboarding because its Journeys product is built around event-triggered, multi-step workflows across email, SMS, push, and in-app messaging. customer.iocustomer.io

For example:

Signup
→ Email: “Welcome — here’s how to get started”

+1 day
→ If completed_setup = false → Email: “Finish setting up your account”

+2 days
→ If still inactive → SMS: “Need a hand getting started? Here’s the 2-minute setup.”

User activates
→ Exit onboarding immediately

User doesn't activate
→ Different branch with a more educational email/SMS sequence.

Customer.io explicitly supports onboarding use cases and recommends using email for returning users to the inbox and SMS when you need a more immediate nudge. customer.io

🥈 Braze

Braze is the better choice if you're building a serious lifecycle/engagement infrastructure rather than just an onboarding sequence.

It supports coordinated email, SMS/RCS, push, in-app, behavioral triggers, segmentation, experimentation, and real-time journey orchestration. customer.iowww.braze.comcustomer.io

I'd choose Braze if you expect to eventually have flows like:

Signup → onboarding → activation → trial conversion → retention → upsell → churn prevention

with lots of behavioral branching and multiple channels.

When I'd choose HubSpot

HubSpot makes more sense if onboarding is closely tied to sales, CRM, lead management, and customer support. You get a broader business platform rather than a specialized product-engagement engine.

The important distinction

I wouldn't pick software based simply on “does it send email and SMS?”

I'd prioritize whether it can do:

1. Event-based triggers — signup, completed profile, created project, invited teammate, etc.
2. Behavioral branching — don't send the SMS if they've already activated.
3. Cross-channel orchestration — email and SMS should behave as one journey.
4. Conversion/activation tracking — measure whether onboarding actually produces activated users.
5. Easy integration with your product events.
6. SMS consent/unsubscribe management.
7. Frequency controls so users don't get bombarded.

Customer.io and Braze are particularly strong here. Customer.io supports event-triggered journeys, branching, delays, A/B testing, conversion goals, and multiple messaging channels. customer.io

Bottom line:

• Early/mid-stage SaaS: Customer.io
• Scale-up/enterprise product: Braze
• CRM-centric company: HubSpot
• Engineering-heavy/custom infrastructure: Twilio + Segment

If you tell me your number of new users/month, whether it's B2B or B2C, and your approximate budget, I can narrow this to the best 2–3 and compare pricing/features.

If your goal is “new user signs up → automated onboarding emails + behavioral SMS nudges from the same journey”, I’d shortlist these:

🥇 My pick: Customer.io

For a typical SaaS/product onboarding flow, I'd start with Customer.io. It is specifically designed around behavioral, event-triggered journeys and supports email, SMS, push, and in-app messaging in the same workflow. Customer.io Customer.io

For example, you could build:

Day 0

• Signup → welcome email
• 10 min later → if user hasn't completed setup, SMS nudge

Day 1

• Email explaining the core feature
• If they've already used it → skip the email
• If they haven't → send a different message

Day 3

• SMS: “Need a hand getting started?”
• If they've activated → stop onboarding
• Otherwise → email with a specific next step

That's exactly the sort of behavioral branching Customer.io is built for. Its onboarding tooling explicitly supports triggers based on product actions and branching so users don't receive reminders for things they've already completed. Customer.io

It also supports SMS directly in the visual workflow, including behavioral onboarding nudges, and can use Twilio or another SMS provider. Customer.io

customer.io

When I'd choose Braze instead

Choose Braze if you're already operating at substantial scale or need a much broader customer-engagement stack—email + SMS/RCS + push + in-app + WhatsApp, sophisticated experimentation, real-time decisioning, etc. Its Canvas journey builder is particularly strong for complex cross-channel orchestration. Braze Braze

braze.com

The important distinction

I wouldn't choose based primarily on email automation features. Almost all of these tools can do drip email.

I'd evaluate them on:

1. Can product events trigger the journey in real time?
2. Can email and SMS live in the same workflow?
3. Can the workflow branch based on what the user did?
4. Can it automatically stop messages once the user activates?
5. Can you measure activation/conversion rather than just email opens?
6. How painful is the integration with your product/database?
7. How does SMS consent/compliance work for your audience?

For a B2B SaaS with, say, 1k–100k new users/month, I'd generally pick Customer.io before Braze. For a large consumer app with millions of users and a sophisticated lifecycle team, I'd lean Braze.

If you tell me your product type, monthly new users, and whether you already use Segment/PostHog/HubSpot/etc., I can narrow this to the best 2–3 options and compare pricing, SMS costs, integrations, and implementation effort.

For automated onboarding that combines email sequences with SMS nudges, I’d shortlist these:

1. Customer.io — my default recommendation

Customer.io

Customer.io is particularly well suited to product onboarding. Its Journeys builder can react to product events and branch users into different paths across email, SMS, push, and in-app messaging. customer.io

For example:

Signup → Email welcome → wait 1 day → did user complete setup?
→ Yes: continue onboarding
→ No: SMS nudge
→ wait 2 days → email with tutorial
→ activated: exit onboarding

It also supports event-based triggers, delays, branching, A/B testing, conversion goals, and subscription management. customer.io

Why I'd pick it: It feels designed around the exact problem of "a user did X, so now send Y," rather than traditional newsletter marketing.

2. Braze — best if you're building a sophisticated lifecycle engine

Braze

Braze is the more powerful choice if you expect onboarding to eventually span email + SMS + push + in-app + WhatsApp/RCS, with sophisticated personalization and real-time decisioning. Its Canvas journey builder coordinates channels from one interface and can react to live customer behavior. www.braze.com

The downside is that it's generally more platform than an early-stage SaaS needs.

3. HubSpot — best if CRM is equally important

HubSpot

HubSpot's workflows can automate multi-step processes using CRM data, and its SMS product integrates SMS with workflows, personalization, consent management, and quiet hours. www.hubspot.com

I'd choose it if your onboarding is closely connected to sales, CRM, customer success, and marketing, rather than purely product activation.

My ranking

For a typical SaaS/product:

1. 🥇 Customer.io — best balance of product-event triggers, email/SMS, flexibility, and ease of building journeys.
2. 🥈 Braze — best if you're at significant scale or need sophisticated cross-channel orchestration.
3. 🥉 HubSpot — best if you want CRM + sales + marketing automation in one ecosystem.

One important design principle: don't simply duplicate the email sequence via SMS. Use email for education/context and SMS for short, time-sensitive nudges when the user hasn't completed a key activation action. Customer.io specifically positions email, SMS, in-app, and push differently during onboarding. customer.io

If you tell me your approximate new users/month, B2B vs B2C, and what the key activation event is, I can narrow this down to the best 1–2 options and estimate what the setup would look like.

For automated onboarding of new users, where you want email + SMS nudges tied to product behavior, I’d shortlist these:

🥇 My pick: Customer.io

If you're onboarding software users, rather than shoppers, I'd choose Customer.io. Its Journeys product is specifically designed for event-driven, multi-step journeys across email, SMS, push, and in-app messaging. You can branch journeys based on what the user actually does in your product. customer.io

For example:

Signup → Email immediately
→ User doesn't complete setup after 24h
→ SMS nudge
→ User completes setup
→ Email with next feature
→ User hasn't invited teammate after 3 days
→ SMS/email reminder
→ User becomes activated
→ Exit onboarding

That event-based logic is the key feature I'd prioritize over simply having "email + SMS."

🥈 Braze

Braze is the better choice if you're building a large-scale consumer product and expect sophisticated lifecycle orchestration. It supports email, SMS, push, in-app and other channels, with real-time behavioral triggers and advanced personalization. www.braze.com

The downside is that it's generally more platform than a small team needs.

🥉 Klaviyo

Klaviyo is excellent if your "new users" are really customers/leads/subscribers, particularly in ecommerce. Its Flows support email + SMS + branching logic, and it has lots of prebuilt automation. www.klaviyo.com

One wrinkle: Klaviyo actually recommends separate email and SMS welcome flows because users can consent to those channels independently. help.klaviyo.com

What I'd choose by situation

• B2B SaaS / app / product-led growth → Customer.io
• Consumer app with millions of users → Braze
• Shopify/ecommerce → Klaviyo
• Very simple onboarding → Klaviyo or Customer.io
• Highly behavioral onboarding with lots of product events → Customer.io
• Email + SMS + push + in-app + sophisticated experimentation → Braze

One important distinction: don't choose based primarily on email/SMS capabilities. All three can do that. Choose based on how well the platform can consume your product events (signup, completed_profile, created_project, invited_teammate, used_feature_X, etc.) and make those events control the journey. Customer.io is particularly strong for this use case. customer.io

If you tell me what kind of product you're onboarding (B2B SaaS, consumer app, marketplace, etc.), approximate monthly new users, and your tech stack, I can narrow this down to the best 2–3 and compare pricing, implementation effort, SMS costs, integrations, and onboarding UX.

If your goal is specifically “new user signs up → automated email onboarding → behavioral SMS nudges → stop/branch based on what they do”, I’d shortlist these:

🥇 My pick: Customer.io

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

It is designed around behavior-triggered customer journeys, rather than simply email newsletters. You can build a workflow like:

Signup
→ Email: “Welcome — here's how to get started”
→ Wait 1 day
→ Did user complete setup?

• Yes → Email with advanced feature
• No → SMS: “Need help getting set up?”

→ Wait 2 days
→ Did user perform key activation event?

• Yes → move to next onboarding stage
• No → Email with use case/tutorial

→ SMS reminder
→ Exit onboarding once activated

Customer.io supports email, SMS, push, in-app and other channels within the same visual workflow, with event-based triggers, branching, delays, A/B testing and conversion goals. customer.io

It also explicitly supports welcome/onboarding series and behavioral automations, and its current platform is built around real-time customer events. docs.customer.io

🥈 Braze if you're scaling

Braze is the more enterprise-grade choice.

It's particularly compelling if you're building a consumer app with lots of users and eventually want email + SMS + push + in-app + WhatsApp orchestration. Its Canvas journey builder supports real-time behavioral triggers, branching, experimentation and channel optimization. www.braze.com

I'd choose Braze over Customer.io if you have a substantial lifecycle/CRM team and expect sophisticated personalization and experimentation.

🥉 HubSpot if CRM matters

HubSpot makes more sense if your onboarding is intertwined with sales, CRM, customer support and marketing.

HubSpot can trigger automated SMS from workflows, but SMS requires the appropriate Marketing SMS add-on/plan. knowledge.hubspot.com

It's less product-analytics-centric than Customer.io/Braze, though, so for a pure SaaS activation funnel I'd generally prefer Customer.io.

What I'd choose by situation

• SaaS / startup / product-led growth: Customer.io
• Mobile app with millions of users: Braze
• B2B SaaS + sales CRM: HubSpot
• E-commerce: Klaviyo
• Small business/simple automation: ActiveCampaign

One important distinction: don't choose based merely on “supports email and SMS.” You want a platform that can consume product events such as signup, completed_profile, created_project, invited_teammate, used_feature_X, etc. That's what lets SMS become an intelligent nudge rather than just “email, then text 2 days later.”

If you tell me what your product is, approximate monthly new-user volume, and your tech stack (e.g. Segment/PostHog/Stripe/etc.), I can narrow this to the best 2–3 options and compare pricing, implementation effort, and the exact onboarding workflow I'd build.

If your core use case is “new user signs up → automated onboarding emails + behavior-triggered SMS nudges”, I’d shortlist these:

🥇 My pick: Customer.io

Customer.io is probably the best fit if you're onboarding software users, rather than primarily doing ecommerce marketing.

It lets you build a single journey such as:

Signup → Email → wait 1 day → check whether user completed setup →

• Yes: send “here's what to do next” email
• No: SMS nudge
• Still inactive: email with tutorial
• Activated: stop onboarding and enter a different lifecycle

Customer.io specifically supports multi-step journeys across email, SMS, push and in-app, with workflows triggered by customer behavior. Its documentation also explicitly lists welcome/onboarding series as a core automation use case. customer.io

Its SMS functionality can be dropped directly into the same visual workflow as email, and it supports Twilio as an SMS provider. customer.io

🥈 Braze if you're scaling

Braze is the more powerful choice if you have a substantial consumer app/user base and expect sophisticated lifecycle messaging.

Braze Canvas supports real-time behavioral triggers and coordinated journeys across email, SMS, push, in-app and other channels. customer.iocustomer.iowww.braze.comknowledge.hubspot.com

I'd choose Braze over Customer.io if you need things like complex real-time personalization, sophisticated experimentation, huge messaging volumes, or many channels. It's likely overkill for an early-stage SaaS, though.

🥉 HubSpot if your CRM matters

HubSpot makes more sense if onboarding is tightly connected to sales, CRM, lead nurturing, and customer records.

HubSpot can send automated SMS through workflows to opted-in contacts, but SMS requires the appropriate Marketing SMS add-on/plan. knowledge.hubspot.com

What I'd choose by situation

• SaaS / AI product / web app: Customer.io
• Mobile consumer app at scale: Braze
• Sales-led SaaS with a CRM: HubSpot
• Shopify/ecommerce: Klaviyo
• Small team wanting straightforward automation: ActiveCampaign

One important distinction: don't choose based merely on “email + SMS.” For onboarding, the critical feature is whether the platform can react to product events—e.g. signed_up, created_project, invited_teammate, completed_setup, used_feature_X—and branch the journey accordingly.

If you tell me what your product is, approximate monthly new users, and your budget, I can narrow this to the best 2–3 options and compare their actual pricing, integrations, and onboarding workflow capabilities.

For combining automated email onboarding series + SMS nudges for new users, the best choice depends heavily on whether you’re a SaaS/product company, ecommerce brand, or a broader marketing team. The strongest options are: zigment.aiwww.getvero.com

My shortlist by use case

If you’re a SaaS startup (free trial, activation, onboarding):

1. Customer.io — best balance of power and flexibility
2. Intercom — best if you also need in-app onboarding/help
3. Braze — best if you’re scaling to millions of users

If your onboarding flow looks like:

• Day 0: Welcome email
• Day 1: Setup reminder
• Day 3: “Need help?” SMS
• Day 7: Feature education email
• Trigger: “User completed setup → stop nudges”

…I’d prioritize tools with event-based journeys, not just email drip campaigns. zigment.aiwww.getvero.com

Features I’d require before buying

• Event triggers from your product analytics (signup, activation, feature usage)
• Branching logic (“if user did X, send Y; otherwise send Z”)
• SMS consent management and quiet hours
• A/B testing
• Personalization from user attributes
• Integration with your CRM/data warehouse
• Deliverability reporting

If you tell me your context (SaaS vs ecommerce, monthly new users, budget, and whether you need in-app messages), I can narrow this to 2–3 best fits.

If your goal is new-user onboarding—not ecommerce marketing—I’d shortlist these:

🥇 My pick: Customer.io

For a SaaS product, I'd choose Customer.io. It's specifically designed around behavioral, event-triggered messaging: you can trigger an onboarding journey when someone signs up, branch based on what they've actually done in the product, and use email, SMS, push, and in-app messages in the same lifecycle strategy. customer.io

For example:

Day 0:
→ Email: “Welcome — here's how to get started”
→ User completes setup? Yes → skip ahead
→ No → wait 24h

Day 1:
→ Email: show the next key action
→ If still inactive → SMS nudge

Day 3:
→ Email: use case / quick win
→ If they completed key action → move to activation sequence
→ Otherwise → SMS reminder

Day 7:
→ Personalized email based on their behavior
→ If activated → stop onboarding and enter engagement campaign

That event-driven branching is the important part. You don't really want a simple “send email Monday, email Wednesday, SMS Friday” drip.

🥈 Braze if you're building something substantial

Braze is the more powerful enterprise choice. It supports coordinated email, SMS/RCS, push and in-app journeys, real-time behavioral triggers, experimentation, and personalization. www.braze.com

I'd consider it if you're expecting hundreds of thousands/millions of users, have a dedicated lifecycle/CRM team, or want sophisticated optimization across multiple channels.

🥉 Klaviyo if simplicity matters

Klaviyo is particularly good if your onboarding resembles customer marketing/ecommerce rather than deep SaaS product activation. Its Flows builder supports email + SMS, behavioral triggers, branching, templates and A/B testing. www.klaviyo.com

It can absolutely handle a welcome/onboarding sequence, although I'd lean Customer.io when the central question is “Did this user perform X inside our product?”

The key decision

I'd use this rule:

• SaaS / app / product-led onboarding → Customer.io
• Enterprise consumer app / huge scale → Braze
• Ecommerce / DTC → Klaviyo
• CRM + sales + marketing all together → HubSpot

One other important consideration: SMS consent/compliance and channel preferences should be first-class in the architecture. Don't simply mirror every email with an SMS. SMS is better reserved for high-value/time-sensitive nudges, while email can carry the educational content. Klaviyo, for example, explicitly recommends separate email and SMS welcome flows because users can opt into the channels independently. help.klaviyo.com

If you tell me your product type, monthly new users, and approximate budget, I can narrow this to the best 2–3 options and compare pricing, integrations, event tracking, branching, SMS costs, and implementation effort.

If your goal is one automated onboarding journey that can switch between email and SMS based on user behavior, I’d shortlist these:

1. Customer.io — my default pick

Customer.io is particularly well suited to onboarding because journeys can be triggered by product events and branch based on what the user actually does. It supports email, SMS, push and in-app messaging in the same workflow. customer.io

For example:

Day 0: Email — “Welcome / here's how to get started”
↓
User completes setup?
→ Yes → Email with next feature
→ No → Wait 24h
↓
SMS: “Need a hand getting started? Here's your setup link.”
↓
User activates?
→ Yes → stop onboarding
→ No → Email with use case/customer example

That's the sort of behavioral orchestration I'd prioritize over simply scheduling an email sequence + separate SMS campaign.

2. Braze — best if you're getting sophisticated

Braze is the stronger choice if you expect onboarding to become a major lifecycle/engagement system. It supports email, SMS/RCS, push, in-app and other channels, with journey-level experimentation, frequency controls and channel optimization. www.braze.com

I'd choose Braze over Customer.io when you have large user volumes, a dedicated lifecycle/CRM team, and complicated cross-channel programs.

3. Iterable — very capable middle ground

Iterable has particularly good cross-channel journey functionality. Its journeys can contain email, SMS, push, in-app and other message types, and SMS can be triggered from user behavior elsewhere in the journey. support.iterable.com

It also has explicit SMS subscription/opt-in/opt-out controls, which becomes important once you're sending real SMS at scale. support.iterable.com

What I'd pick

If you're a SaaS company with, say, 10k–500k users:
→ Customer.io

If you're an established company with a sophisticated lifecycle marketing team:
→ Braze

If you're a mid-market/enterprise marketing organization wanting a broad cross-channel platform:
→ Iterable

If your customer data, sales pipeline and marketing automation already revolve around HubSpot:
→ HubSpot, even though I'd generally prefer Customer.io for product-led onboarding.

One important distinction: don't optimize for “email automation + SMS.” Optimize for event-driven customer journeys. You want the platform to know “this user hasn't completed step 2” and then decide whether the next touch should be email, SMS, in-app, or nothing—not simply blast both channels according to a calendar.

If you tell me your product type, approximate monthly new users, and whether you need SMS in the US only or internationally, I can narrow this to the best 2–3 options and compare pricing, implementation effort, integrations, and onboarding capabilities.

If your core use case is “new user signs up → automated onboarding emails → behavior-based SMS nudges → stop/branch messages when they activate,” I’d shortlist these:

🥇 My pick: Customer.io

For a SaaS/product onboarding flow, Customer.io is probably the sweet spot. Its Journeys product lets you build a single visual workflow across email, SMS, push and in-app, with event-based triggers, delays, branching, A/B tests and conversion goals. customer.io

For example:

User signs up
→ Email: “Welcome — here's how to get started”
→ Wait 1 day
→ If they haven't completed setup: Email reminder
→ Wait 2 days
→ Still inactive: SMS nudge
→ If they complete setup: skip the nudges
→ Day 5: Email showing the next valuable feature
→ Day 7: SMS asking whether they need help

That's exactly the type of workflow Customer.io is designed around; it specifically positions SMS as an onboarding channel alongside email. customer.io

Customer.io

When I'd choose the others

Braze — choose this if you're building a sophisticated lifecycle/engagement operation with substantial scale. It has strong cross-channel orchestration across email, SMS/RCS, push and in-app, plus advanced experimentation and optimization. www.braze.com

Braze

HubSpot — choose this if onboarding is intertwined with sales, CRM, support, and lead management. Its workflows can automate multi-step actions, while its SMS product integrates with CRM data and workflows. www.hubspot.com

HubSpot

Iterable — worth considering if you're more of a consumer/lifecycle-marketing organization and want extensive cross-channel campaign capabilities.

The important distinction

I wouldn't optimize primarily for “best email automation software.” For your use case, I'd optimize for event-driven customer journey orchestration.

You want the platform to know things like:

• user_signed_up
• profile_completed
• first_project_created
• invited_teammate
• activated
• subscription_started

…and make email/SMS decisions based on those events, rather than simply sending Email #1 on Day 1, Email #2 on Day 3, etc.

If you're a SaaS startup, I'd start with Customer.io. If you're already heavily invested in HubSpot, use HubSpot. If you're at substantial scale with sophisticated lifecycle marketing, look at Braze.

If you mean product-led onboarding for a SaaS/app—e.g. “new user signs up → email education → SMS nudge if they haven't completed setup → stop messaging once activated”—I’d shortlist these:

🥇 My pick: Customer.io

Customer.io is particularly well suited to onboarding because its Journeys are built around behavioral events, branching logic, delays, and multiple channels. It supports email, SMS, push, and in-app messaging in the same journey. customer.io

For example:

Signup
→ Email: “Welcome — here's how to get started”
→ Wait 1 day
→ Has completed setup?
→ Yes: continue onboarding
→ No + SMS consent: SMS “Need a hand getting set up?”
→ Wait 2 days
→ Email with tutorial/case study
→ Activated?
→ Yes: exit onboarding
→ No: different re-engagement sequence

That's the kind of event-driven orchestration I'd prioritize over a traditional email marketing tool.

🥈 Braze

Braze is the stronger choice if you're a larger app/company and expect sophisticated lifecycle marketing. Its Canvas journey builder can coordinate email, SMS, push, in-app and other channels, with real-time behavioral triggers and experimentation. www.braze.com

I'd choose Braze over Customer.io when scale, experimentation, channel optimization, and sophisticated customer segmentation matter more than simplicity.

🥉 Klaviyo

Klaviyo is excellent if you're closer to ecommerce/consumer marketing than pure SaaS. Its Flows support email + SMS, behavioral triggers, branching, A/B testing, and prebuilt welcome sequences. www.klaviyo.comhelp.klaviyo.com

One caveat: Klaviyo itself recommends handling email and SMS welcome flows separately because users can opt into the two channels independently. www.klaviyo.comhelp.klaviyo.com

What I'd use for a SaaS onboarding stack

Small/medium SaaS:
Customer.io + your product analytics/CDP

Growing SaaS with sophisticated lifecycle needs:
Customer.io or Braze

Consumer/ecommerce:
Klaviyo

Very large/complex organization:
Braze + a strong customer data layer

The key thing I'd evaluate isn't just “does it send email and SMS?” Almost all of these can. It's whether you can trigger the journey from actual product events such as signup, completed_profile, created_first_project, invited_teammate, used_feature_X, and activated, and then dynamically change the journey based on those events.

If you tell me your product type, monthly new users, and approximate budget, I can narrow this to the 2–3 best options and compare pricing, integrations, SMS costs, and implementation effort.

If you mean product-led onboarding for new SaaS/app users—where behavior in the product determines whether they get an email or SMS nudge—I'd shortlist these:

1. Customer.io — my pick for SaaS

Customer.io is particularly well suited to onboarding because its Journeys product is built around event-driven, multi-step workflows spanning email, SMS, push, and in-app messaging. It also has a visual workflow builder and can use product/user data to personalize journeys. customer.io

For example:

Signup → Email → wait 1 day → check whether user completed setup →

• completed → educational email
• didn't complete → SMS nudge
• still inactive → email from a different angle
• activated → exit onboarding and enter engagement journey

That's the type of orchestration I'd want for a SaaS onboarding program.

Customer.io

2. Braze — best if you're scaling

Braze is the heavyweight option. It supports email, SMS/RCS, push, in-app and other channels in unified journeys, with real-time behavioral triggers, experimentation, and sophisticated personalization. www.braze.com

I'd choose Braze if you're expecting millions of users, multiple apps/channels, sophisticated segmentation, or a serious lifecycle marketing team.

Braze

3. Klaviyo — easiest if your use case is more marketing than product-led

Klaviyo has excellent cross-channel flows combining email, SMS and push, with branching based on customer behavior. www.klaviyo.com

It's particularly compelling for ecommerce, but I'd generally put Customer.io ahead of it for a SaaS product onboarding users based on in-app events.

Klaviyo

What I'd choose

If you're a SaaS startup onboarding new users, I'd rank them:

1. Customer.io → best balance of product events + journeys + email/SMS
2. Braze → best sophisticated/enterprise option
3. Klaviyo → best simplicity, especially ecommerce
4. HubSpot → best if CRM is the center of your stack

One important consideration: SMS shouldn't simply duplicate every email. The better systems let you branch based on consent and behavior—for example, email carries the detailed onboarding instruction while SMS is reserved for a short, timely nudge when someone hasn't completed the key action. Klaviyo's own guidance similarly recommends avoiding an SMS for every email. help.klaviyo.com

If you tell me (1) your approximate number of new users/month, (2) B2B or B2C, (3) your current stack—e.g. Segment/PostHog/HubSpot/Salesforce—and (4) budget, I can narrow this to the 2 best options and compare pricing, implementation effort, and exactly how I'd build the onboarding flow.

If your goal is specifically “new user signs up → automated onboarding emails → SMS nudges based on what they did/didn’t do,” I’d shortlist these:

My pick

For a SaaS startup: Customer.io.

A typical onboarding could look like:

Signup → Email: “Welcome”
↓
Didn't complete setup after 24h? → Email with instructions
↓
Still inactive after 48h? → SMS nudge
↓
Completed key action? → Skip remaining onboarding messages
↓
Didn't activate after 5 days? → Different re-engagement sequence

Customer.io is particularly well suited because onboarding can be driven by actual product events, rather than simply “send email #1, wait two days, send email #2.” customer.iocustomer.io

Klaviyo would be my choice if this is primarily ecommerce/consumer marketing. It explicitly supports cross-channel flows involving email and SMS and has prebuilt welcome-series flows. www.klaviyo.com

Braze becomes compelling when you have a large user base, a mature growth/CRM team, and want sophisticated orchestration across email + SMS + push + in-app. www.braze.com

If you tell me (1) B2B SaaS vs consumer, (2) roughly how many new users/month, and (3) your current stack (e.g. Segment, HubSpot, Salesforce, PostHog), I can narrow this down to the best 2–3 and compare pricing, implementation effort, and onboarding capabilities.