Firma.dev
6.3#16 in e-signature apis softwareFrom €100 a monthWebAPI
VisitFirma.dev vs OpenSign
What both publish
| Fact | Firma.dev | OpenSign |
|---|---|---|
| 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. |
Firma.dev plans
- Pay as you go€0.05, paid once
- Priority Support€100 a month
OpenSign plans
- FreeFree
- Professional$9.99 a month
- Teams$19.99 a month
- EnterprisePriced on request
Pick Firma.dev if…
You want what its maker publishes above — check its page for the details.
Pick OpenSign if…
OpenSign may suit individuals and businesses that need PDF signing, reusable templates, or API-based signing workflows. It also offers self-hosting instructions for those who want to run it on Linux, macOS, or Windows.