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Signkoi
Developer docs

Signkoi API

Build e-signatures into your product with the Signkoi REST API: create and send envelopes, use templates, embed signing and receive signed webhooks.

On this page

The Signkoi API is a REST API for everything you can do with envelopes on the website: upload PDFs, add recipients and fields, send for signature, follow progress, and download the signed PDF with its certificate of completion. CRMs, HR tools, booking systems and your own backend can all send documents for signature without anyone opening Signkoi.

Quickstart API reference

What you can build

  • Send contracts from your product. Generate a PDF, create an envelope with recipients and signature fields, and send it in one request.
  • Reuse templates. Prepare a document once on the website, then fill its roles with real people through the API.
  • Embed signing. Open the signing page inside your app or on a tablet for in-person signing.
  • Stay in sync. Signed webhooks tell your system the moment something is viewed, signed, declined or completed.

API basics

API basics
Base URLhttps://signkoi.com/api/v1
AuthenticationAPI key as Authorization: Bearer <key> — see Authentication
FormatJSON in and out (Content-Type: application/json); file uploads also accept multipart/form-data
IDs and timesPublic UUIDs; timestamps are ISO 8601 in UTC
VersionSignkoi-Version: 2026-11-14 on every response — see the changelog
ErrorsOne error shape with a stable code — see Errors
SpecOpenAPI 3.1 for Postman, Insomnia or code generators

Check your key with your first call:

Shell
curl https://signkoi.com/api/v1/me \
  -H "Authorization: Bearer $SIGNKOI_API_KEY"

Next steps