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Surveys · head to head

Formstack vs Mailgun

Formstack logo

Formstack

Surveys

Form builder with document generation and e-signature

From
On request
Free plan
No
Full reviewWebsite
Mailgun logo

Mailgun

Marketing

Email delivery built for developers

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Only Mailgun has a free tier, so it costs nothing to try first.
  • Each has a real cost: Formstack more expensive than form builders that only collect, which is the fair comparison for simple use; Mailgun free tier limited to 100 emails per day, restricting high-volume use cases
  • Prices and features above were last checked on 29 August 2026.

Where they differ

Only the attributes on which Formstack and Mailgun actually diverge.

Attributes where Formstack and Mailgun differ
AttributeFormstackMailgun
Starting priceOn requestFree
Pricing modelTiered monthly subscription published on the vendor site; HIPAA-capable plans priced separatelysubscription
Free tierNoYes
PlatformsWeb, CloudWeb
CategorySurveysMarketing

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 Formstack

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

Only in Mailgun

Nothing recorded that Formstack does not also cover.

What people use each for

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

Formstack

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

Mailgun

  • Transactional email delivery and SMTP relaynot Formstack
  • Email marketing at scale for developers and enterprisesnot Formstack

Where each one falls short

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

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

Mailgun

  • Free tier limited to 100 emails per day, restricting high-volume use cases
  • Log retention minimal on lower tiers (1 day on Free and Basic plans)
  • Add-on pricing for email validations and extra emails can accumulate quickly for high-traffic users

Pricing, plan by plan

Formstack

On request

No published plan breakdown. See the Formstack review.

Mailgun

Free
  • FreeFree
    • 100 emails per day
    • Basic APIs
    • SMTP relay
  • Basic$15/monthly
    • 10,000 emails per month
    • No daily limits
    • Monthly overage options
  • Foundation$35/monthly
    • 50,000 emails per month
    • 1,000 custom domains
    • Email template builder
  • Scale$90/monthly
    • 100,000 emails per month
    • SAML SSO
    • 5,000 email validations

Which should you pick?

Choose Formstack if

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

Choose Mailgun if

  • You want to start without paying.
Mailgun review

Questions people ask

Is Formstack or Mailgun better?
Neither clearly leads. Formstack starts at On request and Mailgun at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Formstack or Mailgun?
Mailgun has a free tier; the other does not. Paid plans start at On request for Formstack and Free for Mailgun.
Does Formstack or Mailgun run on more platforms?
Formstack runs on Web, Cloud. Mailgun runs on Web.
Can I use Mailgun for free?
Yes. Mailgun has a free tier, so you can try it without paying. Formstack starts at On request.
What is Formstack best used for?
Formstack is most often used for processes where a submitted form must become a signed document, regulated intake needing hipaa-capable handling, salesforce shops wanting forms and documents inside the crm. Of those, processes where a submitted form must become a signed document and regulated intake needing hipaa-capable handling are not what Mailgun is typically brought in for.
What can Formstack do that Mailgun cannot?
Formstack covers Form builder, Document generation, E-signature, Workflow routing.

Answered from the vendors’ own pages

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.

Mailgun: What happens when I exceed my monthly email quota?

Mailgun allows monthly overage options on paid plans. Extra emails are charged from $1.30 to $1.10 per 1,000 emails depending on plan tier. Enterprise customers negotiate custom rates.

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.

Mailgun: Can I upgrade from Free to a paid plan and when does billing begin?

Yes, you can upgrade to paid plans anytime. The first month is free on Foundation ($35/month) and Scale ($90/month) plans, with billing starting on month two.

Source
Formstack: Is it HIPAA compliant?

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

Mailgun: What currencies and billing periods does Mailgun support?

Mailgun supports monthly billing in USD, EUR, and GBP. Charges are prorated for mid-month signups. Annual billing options are not explicitly listed on the pricing page.

Source
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