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Quickstart: curl / any language

The whole API is plain JSON over HTTPS with bearer auth. If your language can curl, it can send.

Facts verified 2026-07-17 — corrections: hello@emailfast.dev

Send

curl https://api.emailfast.dev/v1/emails \
  -H "Authorization: Bearer ef_sandbox_..." \
  -H "Content-Type: application/json" \
  -d '{
    "to": "ada@example.com",
    "to_name": "Ada",
    "subject": "Welcome!",
    "html": "<h1>Hi {{name}}</h1>",
    "data": { "name": "Ada" },
    "message_stream": "transactional",
    "idempotency_key": "signup-42"
  }'

{ "id": "msg_01j…", "status": "queued", "idempotent_replay": false }

a 202 from the API means the send is committed to a durable, partitioned outbox before we answer — a crash can't lose it, and a retry with the same idempotency key can't double-send.

Read the timeline

curl https://api.emailfast.dev/v1/messages/msg_01j… \
  -H "Authorization: Bearer ef_sandbox_..."

Returns the message plus its full event history — admitted, rendered, delivered, opened (human opens only: open tracking that refuses to lie: privacy-proxy prefetch “opens” are detected and not counted as human reads).

Batch

curl https://api.emailfast.dev/v1/emails/batch \
  -H "Authorization: Bearer ef_sandbox_..." \
  -d '{ "messages": [ { "to": "a@example.com", "subject": "…", "html": "…" },
                      { "to": "b@example.com", "subject": "…", "html": "…" } ] }'

Up to 500 per call, per-item results, per-recipient idempotency.

Suppressions

curl https://api.emailfast.dev/v1/suppressions \
  -H "Authorization: Bearer ef_sandbox_..."

Suppression is enforced at admission for every ingress — every send — REST, SMTP, browser SDK, compatibility endpoints, broadcasts, automations — passes through one admission gate: idempotency, suppression, quota, and content policy in a single checkpoint no ingress can skip.

Everything else

The complete surface — templates, contacts, broadcasts, journeys, webhooks, validation — is in the OpenAPI spec. Every endpoint follows the same conventions you just used.