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E-signatures, built into your software

Build BuiltSign into your own product. Test for free with a sandbox key on the same API as production, without real invitations and without cost.

Request sandbox accessAPI documentation

REST API v1 · Webhooks · Node SDK · Zapier · MCP

curl -X POST https://api.builtsign.com/v1/signing-requests \
  -H "X-API-Key: bs_xxxxxxxxxxxxxxxxxxxxxxxx" \
  -H "Content-Type: application/json" \
  -d '{ "document_id": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx", "signers": [{ "name": "Test", "email": "test@example.com" }] }'

What you get

Everything you need to build signing into your own product and test your integration: upload documents, create, send and cancel requests, and receive events.

Sandbox key

An API key to test your integration with, without real invitations and without cost.

REST API v1 with OpenAPI

The same endpoints as production, described in an OpenAPI specification you can import into Postman or your own code generator.

Node SDK

The @builtsign/node package: a TypeScript client for every API endpoint, with built-in retry logic.

Webhooks

Receive an event as soon as something changes. You register webhooks with your sandbox key through POST /v1/webhooks and receive sandbox events only.

Zapier

Connect BuiltSign events to your customers' other apps without code. Still a private integration for now: ask us for the invite link.

MCP server

Let AI assistants upload documents and send signing requests through the Model Context Protocol.

OpenAPI specificationInteractive referenceFull documentation

How it works

  1. 1

    Create an account

    Register your organization with BuiltSign. You start with a 7-day free trial, no credit card needed. The sandbox keeps working after that.

  2. 2

    Request sandbox access

    Fill in the form on this page with the email address of your account. We usually reply within one business day.

  3. 3

    Create your sandbox key

    Once approved, you create a sandbox key yourself under Settings → API Keys. Two-factor authentication is required for this.

  4. 4

    Go live

    Production access to the API is part of the Enterprise plan. Get in touch as soon as your integration is ready for real customers.

Create an accountContact us about Enterprise

What the sandbox does and does not do

The sandbox runs on the same API as production, but without real-world consequences.

Included

  • The v1 endpoints for documents, signing requests, templates and webhooks
  • Webhooks through POST /v1/webhooks, with is_sandbox: true on upload, create and send
  • The header X-BuiltSign-Mode: sandbox in every successful response

Not included

  • No invitation or reminder emails
  • No ID check and no SMS
  • No legal value: signed documents get a watermark

Good to know

  • Sandbox data is deleted after 30 days
  • Lower limits: 30 requests per minute and 500 per day per key

Request sandbox access

Tell us what you are building. We usually reply within one business day.

Use the address of your BuiltSign account, so we link the sandbox to the right organization.

No account yet?

Create an account first. We link the sandbox to your organization.

Create an account

Prefer email?

Send your integration question straight to our sales team.

sales@builtsign.com

Frequently asked questions

Nothing. You do need a BuiltSign account. It starts with a 7-day free trial, and your sandbox key keeps working after that. Production access to the API is part of the Enterprise plan.
No. Signed documents get a watermark and the verification page shows them as test documents with no legal value.
Sandbox data is deleted after 30 days. So do not keep anything in the sandbox that you will need later.
By default a sandbox key may make 30 requests per minute and 500 per day. Invitations, reminders, ID checks and SMS are never sent from the sandbox.