Clement docs

Clement is API-first: every action a customer can take in the dashboard is available over HTTP, with the same auth and the same handlers. These docs cover everything you need to send your first email, run a campaign, and integrate Clement into your own product or agent.

Quickstart

Sign up, create a key, send your first email — in five minutes.

API reference

Every endpoint, generated from the OpenAPI 3.1 spec.

Send your first email

Single-recipient and multi-inbox fan-out from POST /v1/sends.

Webhooks

Signed event delivery, retries, and the deliveries log.

Errors

The error envelope, every code, and how to recover.

Webhook events

Every event type, what triggers it, and the payload shape.

The shape of the API

  • REST + JSON. No GraphQL, no RPC.
  • Bearer auth. Authorization: Bearer cl_live_…
  • Predictable IDs. Type-prefixed ULIDs — inb_…, cmp_…, snd_… — readable to humans and agents.
  • Idempotent. Idempotency-Key required on side-effect-bearing POSTs.
  • Cursor-paginated. Never offset.
  • Signed webhooks. HMAC-SHA256 over timestamp + body, Stripe-style.
  • Agent-friendly. Stable error codes with doc_urls, ?dry_run, ?confirm, OpenAPI-generated MCP server.

SDKs & tools