Build with FastContracts
Send contracts from your product, collect signatures programmatically, and sync events to your CRM in real time. Full OpenAPI 3.0 spec, HMAC-signed webhooks, and copy-paste examples in Node, Python, and cURL.
What you can build
The same e-signature and audit infrastructure our dashboard uses, exposed as an API.
REST API
Create contracts from templates, route them for signature, and collect signed PDFs — all programmatically. Versioned at /api/v1.
Webhooks
14 real-time events across contract and signature lifecycle plus email delivery. HMAC-SHA256 signed, exponential-backoff retries.
Audit-trail export
Pull the tamper-evident audit log for any contract — attribution, intent, consent, timestamps, document hash chain.
Scoped API keys
Separate test and live keys. Per-integration scopes so each connected system only sees what it needs.
OpenAPI 3.0, no SDK needed
Our full OpenAPI spec is served live at /api/v1/docs. Generate a typed client in any language with openapi-generator, or use the interactive playground to try every endpoint with your test key.
Getting started
Create a key in developer settings, copy it into your integration, and fire a test webhook against webhook.site to see the signed payload before wiring up production.
Not a customer yet? Create an account to claim your first test key.