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Developers

Signing in your product, in an afternoon

Send a document with one request. API, webhooks and embedding are included in every plan; test mode lets you try it without a real signature.

For developers

Your product, our signing.

One request sends a document. Embed the signing form on your own pages, so nobody leaves your site. Test mode keeps practice runs out of the real thing, and a signed webhook tells your system the moment it is done.

  • REST API with scoped keys and safe retries
  • Signed webhooks, replayable from a log
  • An embeddable form, a JavaScript and a Python client, an MCP server
DevelopersRead the docs
curl -X POST https://docustay.app/api/v1/documents/send \
  -H "Authorization: Bearer $DOCUSTAY_KEY" \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{
    "templateId": "TEMPLATE_ID",
    "parties": [{ "seat": "signer_1", "name": "Rosa Alvarez", "email": "rosa@example.com" }]
  }'
document.executedSigned webhook · sealed copy ready

Try it safely

Turn on test mode, or use a test API key. Mail goes only to the sender, every page is stamped TEST, and test documents are never counted or billed.

The Developer settings screen with API keys and webhook endpoints
The Developer settings screen with API keys and webhook endpoints

The shape of an integration

Your system decides a document is needed and calls the API with a template and the names and emails of the people. Docustay emails them, runs reminders, shows the signing page and seals the result. When it is done, a signed webhook tells your system, and your system downloads the signed copy. Most integrations are a few dozen lines.

Four ways in

The REST API does everything the app does, within the permissions of a key. Webhooks tell you when something happens. The embeddable signing form shows the signature page inside your own site so nobody is emailed. The SDKs and the MCP server wrap those for JavaScript, Python and AI assistants.

Practise first

Test keys send practice documents that are emailed only to you, are watermarked, and are never counted or billed. Build and check your whole flow with a test key, then swap in a live key.

Send a document

curl -X POST https://docustay.app/api/v1/documents/send \
  -H "Authorization: Bearer $DOCUSTAY_KEY" \
  -H "Idempotency-Key: $(uuidgen)" -H "Content-Type: application/json" \
  -d '{ "templateId": "TEMPLATE_ID", "language": "en", "parties": [{ "seat": "signer_1", "name": "Rosa Alvarez", "email": "rosa@example.com" }] }'

Questions people ask

Is the API included in every plan?

Yes, within your monthly allowance, along with webhooks and embedding.

Is there a sandbox?

Test keys are the sandbox: same API, practice documents.

Where is the API described?

An OpenAPI 3.1 file at /api/openapi.json and a Postman collection.

Keep reading

Get an API key

Create a free workspace, then make a key under Settings, Developers.

Start freeRead the docs