InboxOS
Developer docs

Send your first email in under 60 seconds.

The InboxOS REST API is simple, typed, and built for developers. One endpoint to send, one to track, one to manage domains.

Get API keyView endpoints
Step 1

Get your API key

Sign up and navigate to Settings → API Keys. Generate a key with send scope.

Step 2

Make your first request

POST to /v1/send with your key. Works with curl, fetch, axios — any HTTP client.

Step 3

Receive events

Register a webhook URL in the dashboard. Get real-time delivery, open, and click events.

API Endpoints

All requests require Authorization: Bearer YOUR_KEY

POST/v1/send— Send a transactional email
{
  "to": "user@example.com",
  "from": "hello@yourapp.com",
  "subject": "Your receipt",
  "template": "receipt",
  "vars": { "amount": "$49" },
  "track_opens": true,
  "track_clicks": true
}
GET/v1/messages/:id— Get delivery status for a message
// Response
{
  "id": "msg_01JK9X2QRTZ8N",
  "status": "delivered",
  "opened_at": "2026-05-12T10:45:22Z",
  "clicked_at": null,
  "delivery_ms": 47
}
POST/v1/domains— Add and verify a sending domain
{
  "domain": "mail.yourapp.com"
}
// Returns DKIM/SPF/DMARC DNS records
// to add to your DNS provider
POST/v1/templates— Create or update an email template
{
  "name": "welcome",
  "subject": "Welcome, {{name}}!",
  "html": "<h1>Hi {{name}}</h1>",
  "text": "Hi {{name}}"
}

Webhook events

InboxOS sends HMAC-SHA256 signed events to your webhook URL for every state change.

email.queuedemail.deliveredemail.bouncedemail.openedemail.clickedemail.unsubscribedemail.complained