Firma.dev vs OpenSign
Firma.dev
firma.dev
OpenSign
opensignlabs.comSide by side
| Figure | Firma.dev | OpenSign |
|---|---|---|
| Price from | €100/mo | $9.99/mo |
| Free plan | — | Yes |
| Free trial | Yes | Yes |
| Open source | — | Yes |
| Web | Yes | Yes |
| Windows | — | Yes |
| macOS | — | Yes |
| Linux | — | Yes |
| API | Yes | Yes |
| Self-hosted | — | Yes |
| Plans published | 2 | 5 |
| Spec score · E-Signature APIs Software | 7.9 (#14) | 9.0 (#3) |
| Spec score · Electronic Signature APIs | 7.9 (#17) | 8.9 (#2) |
| API access | Firma.dev describes its product as a plain REST API that can connect to unlisted platforms through a standard HTTP request. | Yes |
| Integrations | Firma.dev lists 27 integrations across seven categories, including MCP, Claude Code, ChatGPT, Salesforce, n8n, Zapier, Bubble, and WordPress. | The Professional plan lists Zapier integration, Dropbox import and custom Gmail or SMTP sending. |
| Product | Firma.dev is an e-signature API for embedding document signing in applications, aimed at developers and SaaS platforms. | OpenSign describes itself as an open-source PDF e-signature solution for signing, storing, and securing documents. |
Plans
OpenSign
- FreeFree
- Professional$9.99 a month
- Teams$19.99 a month
- FreeFree
- EnterprisePriced on request
In their own words
OpenSign
OpenSign is an open-source PDF e-signature solution for signing, storing, and securing documents. Users can create reusable templates with pre-placed widgets and send them through the API to one or many signers. API workflows include self-signing, drafts, signer roles, public template links, and real-time webhook notifications. Templates can be embedded in React, Next.js, HTML, JavaScript, and Angular projects. The documentation lists TLS-encrypted transport, audit trails, IP logging, and tamper-evident signed PDFs; account protection includes two-factor authentication and passkey sign-in. The free plan costs nothing and lists unlimited digital signatures and templates, completion certificates, sequential signing, OpenSign Drive, and email notifications. Its free-plan guide limits invitation emails to 15 per month; bulk sending and public links require a paid plan. Live API tokens require Professional or Teams, though sandbox tokens are available on all plans. OpenSign provides Docker self-hosting instructions for Linux, macOS, and Windows. Some SMTP features are limited to paid plans.