Quickstart: cURL

The API is plain HTTPS and JSON — if you can curl it, you can use it from anything.

$ curl https://api.calder.click/v1/emails \
  -H "Authorization: Bearer calder_sk_test_…" \
  -H "Idempotency-Key: hello-001" \
  -H "Content-Type: application/json" \
  -d '{"from":"app@acme.com", …}'

Expect {"id": "em_…", "status": "queued"} back with HTTP 202. Re-run the identical command and you’ll get the original result with a 200 — try it, that’s idempotency working. Then read the full reference.