Firma vs SignatureAPI (2026): which should you pick?

Pick Firma if

• Fits if you send low volumes from your own SaaS and want no monthly fee
• Works for developers who want webhooks and a TypeScript SDK

Look elsewhere if

• Not for you if you have no developer, as there is no signing app to open
• Watch out: prices are in euros and billed in your currency at the day's exchange rate
• Tight if you need fast support, because one-business-day priority support is EUR 100 a month extra
• Watch out: one envelope is one document however many signers or pages it has

Pick SignatureAPI if

• Fits if you are building signing into your own product
• Works for developers who want to pay per completed envelope

Look elsewhere if

• Not for you if you have no developer, since it is an API with only connectors for no-code
• Watch out: the signatures are eIDAS simple only, not advanced or qualified
• Tight if your envelopes are large, as the limit is 10 documents and 10 signers
• Watch out: annual billing and prepaid credits are not self-serve

Firma

• Prices are listed in euros and billed in your local currency at the current exchange rate, so the dollar amount varies.
• One envelope is one document sent for signature, however many signers or pages it has.
• Priority support with a one-business-day response is a separate €100 per month.
• It is an API product; there is no separate end-user signing app listed.

SignatureAPI

• Only completed envelopes, signed by every recipient, are billed; the $0.25 rate applies after the first 100 each month.
• An envelope holds at most 10 documents and 10 signers.
• The vendor classifies its signatures as eIDAS simple electronic signatures (SES), not advanced or qualified ones.
• Annual billing and prepaid credits are not self-serve; the vendor says to contact it.

Firma

REST API and TypeScript SDK

Send documents from templates or uploaded PDFs, add recipients with roles, set signing order and deadlines, and download signed files and audit trails.

Embedded editors

Template and signing editors drop into your app as an iframe, with custom styling and white-label branding applied.

Unlimited teams

Each of your customers can have an isolated workspace with its own branding and webhook settings at no extra charge.

Webhooks and event stream

Events such as document sent, viewed, signed and complete are pushed as webhooks, and a server-sent event stream covers team activity.

Audit trail and compliance

Every signing request records views, field changes and signatures. The vendor says it aligns with ESIGN, UETA, eIDAS and GDPR.

Zapier and n8n

For no-code use the vendor says Firma connects to Zapier or n8n.

SignatureAPI

Envelope API

One call creates an envelope with up to 10 documents and up to 10 signers, routed in parallel or in sequence.

Document templates

Start from a .docx file with placeholders and fill it with data from your own system before the document goes out for signature.

Accountless signing

Signers open a link and sign from a desktop or phone browser without creating an account.

Sealed documents and audit log

The finished file holds the signed documents and a log of who opened it and what they did, cryptographically sealed against changes.

Branding and languages

Logo and brand colors can be applied to the signing page and recipient emails, and the interface language, date format and time zone can be set.

Webhooks and no-code connectors

Webhooks and emails report signing activity in real time. Power Automate and Zapier connectors and an AI toolkit are offered for non-developers and agents.

Firma

• Pay as you go€0.049

  per envelope, no minimum or contract

  Flat rate at any volume, with unlimited teams, full API access and no per-seat fees. Priced in euros and billed in your currency.

SignatureAPI

• Standard$25

  per month, includes 100 envelopes

  First 100 envelopes included, then $0.25 each. One dashboard user included, extra users $20 each.

• EnterpriseCustom

  Annual contracts, prepaid credits, SLAs and dedicated Slack support, sold through sales.