API Reference

SDKs

Language	Package	Install
Node.js / TypeScript	`retransmit.dev`	`npm install retransmit.dev`

The SDK wraps every endpoint below with typed methods (emails.send, emails.get, batch.send, batch.get, sms.send, sms.get, whatsapp.send, whatsapp.get) and returns { data, error } instead of throwing. Each endpoint page shows the SDK call next to the raw HTTP request.

Base URL

Environment	Base URL
Production	`https://api.retransmit.dev`
Local development	`http://localhost:3002`

All endpoints are versioned under /v1.

Authentication

Every request must include your API key as a Bearer token:


Authorization: Bearer rt_xxxxxxxxxxxxxxxx

Keys are created in the dashboard and shown once. A missing, malformed, or revoked key returns 401 unauthorized:


{
  "error": {
    "code": "unauthorized",
    "message": "Provide your API key as `Authorization: Bearer rt_...`"
  }
}

Response format

Responses are JSON. Errors always have this shape:


{
  "error": {
    "code": "some_error_code",
    "message": "Human-readable explanation"
  }
}

See Errors for the full list of codes.

Endpoints

Method	Path	Description
`POST`	`/v1/emails`	Queue an email
`POST`	`/v1/emails/batch`	Queue up to 10,000 emails in one request
`GET`	`/v1/emails/:id`	Retrieve an email and its event history
`GET`	`/v1/emails/batch/:id`	Batch progress: counts per status
`POST`	`/v1/sms`	Queue an SMS
`GET`	`/v1/sms/:id`	Retrieve an SMS and its event history
`POST`	`/v1/whatsapp`	Queue a WhatsApp message
`GET`	`/v1/whatsapp/:id`	Retrieve a WhatsApp message and its event history
`GET`	`/health`	Health check (no auth required)

Asynchronous sending

Sending returns 202 Accepted with status queued. A worker sends at the provider’s rate and retries transient failures with exponential backoff. A message is marked failed only after all retries are exhausted. Track outcomes by polling the matching GET endpoint or through Webhooks.