Documentation
Quick Start.
Send your first email with SMTPfast in under two minutes.
Overview
SMTPfast is a developer-first email API built for speed and simplicity. Send transactional emails, manage sending domains, and track delivery events through a clean REST API.
The API is compatible with Resend, so you can switch with minimal code changes.
Base URL
text
https://smtpfa.st/api/v1
All endpoints described in these docs are relative to this base URL.
Authentication
Every request requires a Bearer token in the Authorization header. Create an API key from your dashboard or via the API.
Header
Authorization: Bearer sf_live_your_api_key
Send Your First Email
Make a POST request to /v1/emails with the recipient, subject, and body.
curl -X POST https://smtpfa.st/api/v1/emails \
-H "Authorization: Bearer sf_live_your_api_key" \
-H "Content-Type: application/json" \
-d '{
"from": "[email protected]",
"to": ["[email protected]"],
"subject": "Welcome!",
"html": "<h1>Hello from SMTPfast!</h1>"
}'Response Format
All responses are JSON. Successful requests return a 200 status code. Errors include a message field describing the issue.
Success
json
{
"id": "email_abc123"
}Error
json
{
"error": "Invalid API key",
"status": 401
}