SentFast API

The SentFast API sends emails you have already built in the dashboard. Your backend does not carry subjects, HTML or copy: it sends a template id, a recipient and the values of the dynamic variables.

Everything runs against one endpoint:

POST https://sentfa.st/api/v1/email/send

Before you start

You need three things:

1. A project workspace, which owns your templates and your keys.
2. An email template created in the dashboard, with its {{variables}} defined. Its id looks like em_a1b2c3d4.
3. An API key for that project. It is shown once, when you create it.

Send your first email

curl -X POST "https://sentfa.st/api/v1/email/send" \
  -H "Content-Type: application/json" \
  -H "x-api-key: $SENTFAST_API_KEY" \
  -d '{
    "id": "em_a1b2c3d4",
    "to": "customer@example.com",
    "params": { "user_name": "Alex" }
  }'

A successful call returns:

{ "ok": true, "message": "Email \"em_a1b2c3d4\" queued/sent to customer@example.com" }

From then on, changing the wording of that email is an edit in the dashboard. Your backend keeps sending the same id.

Machine-readable references

• openapi.json: the full specification of the endpoint, for client generators and agents.
• Every page here has a markdown version at the same path with .md appended, for example /docs/send-email.md.