Softwr

Marketing · head to head

Customer.io vs Formstack

Customer.io logo

Customer.io

Marketing

Data-driven messaging for teams getting started, scaling and beyond

From
$15/month
Free plan
No
Full reviewWebsite
Formstack logo

Formstack

Surveys

Form builder with document generation and e-signature

From
On request
Free plan
No
Full reviewWebsite

The short version

  • Each has a real cost: Customer.io essentials plan caps at 5,000 profiles (people and objects) and 1,000,000 monthly emails, with overages billed at $0.12 per 1,000 emails beyond that; Formstack more expensive than form builders that only collect, which is the fair comparison for simple use
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which Customer.io and Formstack actually diverge.

Attributes where Customer.io and Formstack differ
AttributeCustomer.ioFormstack
Starting price$15/monthOn request
Pricing modelsubscriptionTiered monthly subscription published on the vendor site; HIPAA-capable plans priced separately
PlatformsWebWeb, Cloud
CategoryMarketingSurveys

Identical on both: free tier (No), user rating (Not yet rated).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Customer.io

Nothing recorded that Formstack does not also cover.

Only in Formstack

  • Form builder
  • Document generation
  • E-signature
  • Workflow routing
  • Salesforce integration
  • Compliance features

What people use each for

The jobs each tool is most often brought in to do.

Customer.io

  • Orchestrating multi-channel customer journeys from signup to retentionnot Formstack
  • Personalizing email and SMS campaigns using customer profilesnot Formstack
  • Triggering automated messages based on user behaviornot Formstack
  • Coordinating cross-team messaging without rebuilding campaignsnot Formstack

Formstack

  • Processes where a submitted form must become a signed documentnot Customer.io
  • Regulated intake needing HIPAA-capable handlingnot Customer.io
  • Salesforce shops wanting forms and documents inside the CRMnot Customer.io

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Customer.io

  • Essentials plan caps at 5,000 profiles (people and objects) and 1,000,000 monthly emails, with overages billed at $0.12 per 1,000 emails beyond that
  • Standard and Premium tiers show custom pricing only, and Enterprise is negotiated rate, so three of the four published tiers require a sales conversation
  • Monthly plans accept credit card only; annual billing via invoice (ACH/wire) requires the annual commitment

Formstack

  • More expensive than form builders that only collect, which is the fair comparison for simple use
  • Document generation and signature sit in higher tiers, so the headline price is not the working price
  • The interface has accumulated features over a long life and shows it
  • Overkill where a form only needs to collect an answer

Pricing, plan by plan

Customer.io

$15/month
  • Essentials$15/month
    • Base profiles starting at 5,000
    • Email sends: 1 million monthly
    • Community and email support
  • Standard$null/month
    • Mid-tier scaling across channels
    • Higher profile and email allowances
    • Email and priority support
  • Premium$null/month
    • Advanced custom workflows
    • Dedicated support
  • Enterprise$null/month
    • Custom pricing for dedicated infrastructure
    • HIPAA compliance
    • Dedicated hardware

Formstack

On request

No published plan breakdown. See the Formstack review.

Which should you pick?

Choose Customer.io if

Nothing in the data separates Customer.io from Formstack on the points above - pick on price and on how each one feels to use.

Customer.io review

Choose Formstack if

  • You need form builder.
  • You work on Web, Cloud.
  • You also want document generation.
Formstack review

Questions people ask

Is Customer.io or Formstack better?
Neither clearly leads. Customer.io starts at $15/month and Formstack at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Customer.io or Formstack?
Customer.io starts at $15/month and Formstack at On request.
Does Customer.io or Formstack run on more platforms?
Customer.io runs on Web. Formstack runs on Web, Cloud.
What is Customer.io best used for?
Customer.io is most often used for orchestrating multi-channel customer journeys from signup to retention, personalizing email and sms campaigns using customer profiles, triggering automated messages based on user behavior, coordinating cross-team messaging without rebuilding campaigns. Of those, orchestrating multi-channel customer journeys from signup to retention and personalizing email and sms campaigns using customer profiles are not what Formstack is typically brought in for.
What can Customer.io do that Formstack cannot?
Formstack covers Form builder, Document generation, E-signature, Workflow routing.

Answered from the vendors’ own pages

Customer.io: How much does Customer.io Essentials cost?

Customer.io Essentials starts at $15/month and includes 5,000 base profiles with 1 million monthly email sends, community and email support, and data-driven messaging tools. Customers can choose monthly or annual billing.

Source
Formstack: What does Formstack cost?

It publishes tiered monthly pricing; document generation and e-signature sit in higher tiers, and HIPAA-capable plans are priced separately.

Customer.io: What are Customer.io's usage-based add-on costs?

Beyond plan limits, Customer.io charges $0.009 per additional profile, $0.12 per 1,000 additional emails, and $10 per 100K AI credits. Messages exceeding plan limits are charged at nominal rates. Billing occurs on the subscription anniversary.

Source
Formstack: What makes it different from a plain form builder?

It generates documents from submissions and collects signatures on them, which is the step that otherwise involves retyping form data into a template.

Customer.io: Does Customer.io offer a startup discount?

Yes, early-stage companies that have raised under $10 million qualify for a full year free through Customer.io's Startup Program with annual billing.

Source
Formstack: Is it HIPAA compliant?

It offers HIPAA-capable plans for regulated data. That is a plan-level feature, not the default.

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