Electronic signature REST API

A REST API (Representational State Transfer) for electronic signature exposes the signature engine's operations as HTTP resources accessible by any programming language. Typical workflows include: envelope creation (POST /envelopes), document upload (PUT /envelopes/{id}/documents), adding signers and fields (POST /recipients), sending for signature (PUT /envelopes/{id}/send), then retrieving the signed document (GET /envelopes/{id}/signed-pdf). Authentication relies on Bearer tokens (OAuth 2.0 / API keys). Webhooks complement the API by pushing events (document signed, rejected, expired) to your backend without polling. A good electronic signature REST API guarantees document integrity via a SHA-256 hash returned at each step and supports timestamped audit trail. Certyneo exposes a complete REST API documented in OpenAPI 3.1 with SDKs available in Node.js, Python and PHP.