# SignatureAPI review (2026): is it worth $25 a month? > E-signature API for developers, with a no-code connector Checked Nov 13, 2026 ยท graded Nov 13, 2026 by ToolGPA. SignatureAPI is an electronic signature service built to be called from other software. Developers create an envelope over a REST API, generate documents from .docx templates and receive the signed file with an audit log. Connectors for Power Automate and Zapier and an AI toolkit cover people who do not write code. - **Category:** E-Signatures & Proposals - **Made by:** Signature API, Inc. - **Website:** https://signatureapi.com - **Runs on:** Web - **Who should skip it:** Not for you if you have no developer, since it is an API with only connectors for no-code. - **Facts last checked:** Nov 13, 2026 ## Pricing As of Nov 13, 2026, SignatureAPI is a paid product with a free trial, starting at $25 per month, includes 100 completed envelopes. - **Pricing model:** Free trial - **Free plan:** None. - **Free trial:** Free test account with no time limit, no card required. | Plan | Price | What you get | | --- | --- | --- | | Standard | $25 per month, includes 100 envelopes | First 100 envelopes included, then $0.25 each. One dashboard user included, extra users $20 each. | | Enterprise | Custom | Annual contracts, prepaid credits, SLAs and dedicated Slack support, sold through sales. | Read from https://signatureapi.com/pricing on Nov 13, 2026. Prices change, so confirm with SignatureAPI before buying. ## Key features - **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. ## Good for - Developers adding signing to a SaaS product - Teams sending a few hundred envelopes a month on a flat per-envelope rate - Low-code teams automating signature requests with Power Automate or Zapier ## Worth knowing - 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. ## ToolGPA grades **GPA: 2.0 out of 4**, graded Nov 13, 2026. SignatureAPI is an e-signature API for developers: Standard is $25 a month with 100 envelopes, then $0.25 each. The free test account has no time limit, and only completed envelopes are billed. Its signatures are eIDAS simple signatures, not advanced or qualified ones, so you write code to use it. - **Value for money: C.** Standard is $25 a month with 100 envelopes included, then $0.25 each, just above the category's $20 middle. Extra dashboard users are $20 each. - **Free plan and trial: C.** A free test account with no time limit and no card, but it is for testing, and sending for real needs Standard. - **Features: C.** Envelope API, templates, signing with no account, sealed documents, audit log, branding and webhooks. An envelope holds at most 10 documents and 10 signers, and signatures are simple only. - **Ease of use: D.** No store rating on record, and it needs developers to write code against an API before anyone signs anything. - **Platforms and integrations: B.** Web and API, with Power Automate and Zapier connectors. These are ToolGPA's own grades. Graded from this listing, whose facts were read from SignatureAPI's own pages on 13 November 2026. Not based on using the product, and shorter than our full reviews. ## Where it stands among e-signature and proposal tools - SignatureAPI's GPA of 2.0 is higher than 19 of the 78 other e-signature and proposal tools we grade, and level with 18. - It stands best on platforms and integrations (B, above 12 of 78) and worst on ease of use (D, above 1). - Its paid plans start at $25 a month, against a middle price of $19 for the category: 34 of the 54 others that charge start lower. - On features, ease of use and platforms it scores 2.0 out of 4. 29 tools score higher and cost less. The category's chart of price against score: https://toolgpa.com/charts/e-signatures ## Keep it, or make your own? **Keep it.** To replace SignatureAPI you would be making connections to other products, each kept working as those products change. That is not a weekend's work, with an AI app builder or without one. That makes this kind of software worth paying for, not this one in particular: 41 of the 78 other e-signature and proposal tools grade higher. It costs $300 a year. - You could make: Templates: an app builder makes this well. - You could not: Connections to other products, each kept working as those products change. - You could not: An AI agent, with the models and the safeguards behind it. - You could not: What a company asks for before it lets staff use something: audit logs. A judgement by ToolGPA from this listing, by rules that are the same for every tool. Nothing was built to test it. ## Works with Power Automate, Zapier **Tags:** Public API, Templates, Workflow automation, AI agents ## Alternatives - [Anvil](https://toolgpa.com/tools/anvil): Document automation and e-signature APIs for developers. [Compare](https://toolgpa.com/compare/anvil-vs-signatureapi) - [Firma](https://toolgpa.com/tools/firma-dev): Pay-per-envelope e-signature API for SaaS products. [Compare](https://toolgpa.com/compare/firma-dev-vs-signatureapi) - [eSignatures.io](https://toolgpa.com/tools/esignatures-io): Pay-per-contract e-signatures with an API and no monthly fee. [Compare](https://toolgpa.com/compare/esignatures-io-vs-signatureapi) - [BoldSign](https://toolgpa.com/tools/boldsign): Low-cost e-signature app and API from Syncfusion. [Compare](https://toolgpa.com/compare/boldsign-vs-signatureapi) - [Dropbox Sign](https://toolgpa.com/tools/dropbox-sign): E-signature app from Dropbox with unlimited requests on paid plans. [Compare](https://toolgpa.com/compare/dropbox-sign-vs-signatureapi) ## Sources The prices, plans, platforms and features above were read from these pages on Nov 13, 2026: - https://signatureapi.com/pricing - https://signatureapi.com - https://signatureapi.com/startups Page: https://toolgpa.com/tools/signatureapi Listed by ToolGPA (toolgpa.com).