Softwr

Marketing · head to head

Customer.io vs Fillout

Customer.io logo

Customer.io

Marketing

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

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

Fillout

Surveys

Form builder that reads and writes records in Airtable, Notion, HubSpot and Salesforce, with unlimited seats on every plan including the free one

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Only Fillout has a free tier, so it costs nothing to try first.
  • 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; Fillout the Business plan is marketed with unlimited responses but the fair use policy names thresholds of 30,000 submissions a month, 250,000 in total, 500 forms per account and 50 GB of uploads a month, above which the vendor may limit or suspend features, so unlimited means unmetered rather than uncapped.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

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

Attributes where Customer.io and Fillout differ
AttributeCustomer.ioFillout
Starting price$15/monthFree
Pricing modelsubscriptionPer month by response count
Free tierNoYes
PlatformsWebWeb, API
CategoryMarketingSurveys

Identical on both: 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 Fillout does not also cover.

Only in Fillout

  • Unlimited seats and forms
  • Database read and write
  • Soft response limits
  • Conditional logic and calculations
  • EU hosting
  • REST API and webhooks

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 Fillout
  • Personalizing email and SMS campaigns using customer profilesnot Fillout
  • Triggering automated messages based on user behaviornot Fillout
  • Coordinating cross-team messaging without rebuilding campaignsnot Fillout

Fillout

  • A team already running on Airtable or Notion that wants forms which update existing records rather than appending new rowsnot Customer.io
  • An organisation with many occasional form builders, where per-seat pricing elsewhere would cost more than the forms are worthnot Customer.io
  • Replacing a survey tool, a scheduling tool and a payment link with one form that does all threenot Customer.io
  • Public forms that must keep collecting through an unexpected traffic spike rather than shutting off at a quotanot 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

Fillout

  • The Business plan is marketed with unlimited responses but the fair use policy names thresholds of 30,000 submissions a month, 250,000 in total, 500 forms per account and 50 GB of uploads a month, above which the vendor may limit or suspend features, so unlimited means unmetered rather than uncapped.
  • EU data residency begins on the Team plan at 250 USD per month, more than three times the Business price, and is not applied automatically; you must upgrade and then raise a support request to be moved.
  • The Team plan is hidden behind a secondary tab that does not render without interaction, so buyers reading the pricing page see Business at 75 USD as the top self-serve tier and only discover the 250 USD step when they ask for single sign-on or EU hosting.
  • The enterprise marketing page lists hosting in the United States, EU, United Kingdom, Australia and Canada, but the security documentation and subprocessor list name only the United States and the EU, so three of those five regions should be confirmed in writing before they are relied on.
  • The vendor is SOC 2 Type 2 but claims neither ISO 27001 nor HIPAA anywhere in its documentation, and it is angel-funded with no disclosed institutional round while the parent company now trades as Zite and ships a separate AI application builder.

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

Fillout

Free
  • FreeFree
    • 1,000 responses per month
    • Unlimited forms and unlimited seats
    • 20 MB per file upload
  • Starter$15/month
    • 180 USD per year billed annually, a stated 20 percent saving on monthly billing
    • 2,000 responses per month
    • Unlimited forms and seats
  • Pro$40/month
    • 480 USD per year billed annually
    • 5,000 responses per month
    • Branding fully removed at this tier
  • Business$75/month
    • 900 USD per year billed annually
    • Marketed as unlimited responses, subject to a fair use threshold near 30,000 per month
    • 1 GB per file upload

Which should you pick?

Choose Customer.io if

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

Customer.io review

Choose Fillout if

  • You need unlimited seats and forms.
  • You want to start without paying.
  • You work on Web, API.
  • You also want database read and write.
Fillout review

Questions people ask

Is Customer.io or Fillout better?
Neither clearly leads. Customer.io starts at $15/month and Fillout at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Customer.io or Fillout?
Fillout has a free tier; the other does not. Paid plans start at $15/month for Customer.io and Free for Fillout.
Does Customer.io or Fillout run on more platforms?
Customer.io runs on Web. Fillout runs on Web, API.
Can I use Fillout for free?
Yes. Fillout has a free tier, so you can try it without paying. Customer.io starts at $15/month.
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 Fillout is typically brought in for.
What can Customer.io do that Fillout cannot?
Fillout covers Unlimited seats and forms, Database read and write, Soft response limits, Conditional logic and calculations.

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
Fillout: Are seats really unlimited?

Yes. The vendor states there are no per-seat charges on any plan, including Free, and forms are unlimited too. Responses per month is the only meter below the Business tier.

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
Fillout: What happens when I exceed my response quota?

Nothing breaks. Forms keep collecting, and you can upgrade, buy bulk submissions or wait for the monthly reset.

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
Fillout: Can I host respondent data in the EU?

Only from the Team plan at 250 USD per month, and only after contacting support to switch. Note that email and payment subprocessors remain in the United States regardless.

Fillout: Is the Business plan really unlimited responses?

It is unmetered, not uncapped. The fair use policy names roughly 30,000 submissions a month as the point at which the vendor may intervene, so treat that as the practical ceiling.

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