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This section documents Courier’s REST API endpoints for sending notifications, managing users, configuring channels, and more. Every endpoint includes request/response schemas, code examples, and authentication details.

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API Keys

To call the Courier API, you need an API key. Grab one from the Courier dashboard.

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SDKs

Courier’s server SDKs wrap the REST API with typed methods for sending notifications, managing users, configuring channels, and more. Install the SDK for your language to get started. 
npm install @trycourier/courier
Courier also offers mobile SDKs (iOS, Android, Flutter, React Native) and client-side browser SDKs. See the SDKs overview for the full list.

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Next Steps

Send a message

Create a user profile

Create a JWT

Update a list

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Rate Limiting

EndpointOperationLimit
Lists APIPOST to subscriptions20 requests/minute
PUT to lists20 requests/minute
Events APIPUT to events20 requests/minute
Brands APIPUT to brands200 requests/minute
Invitations50 invites/15 minutes
Login Attempts5 attempts/5 minutes
Categories20 creations/minute

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Idempotency

Add an Idempotency-Key header to any POST request to ensure it runs only once, even if retried.
cURL
curl --request POST \
  --url https://api.courier.com/send \
  --header 'Authorization: Bearer <YOUR_API_KEY>' \
  --header 'Content-Type: application/json' \
  --header 'Idempotency-Key: <YOUR_UNIQUE_KEY>' \
  --data '{
    "message": {
      "to": { "user_id": "user-123" },
      "template": "WELCOME_TEMPLATE",
      "data": { "name": "Alice" }
    }
  }'
  • Use a unique value (like a UUID) for each logical request.
  • Replaying the same key returns the original response, even if it was an error.
  • Keys expire after 24 hours.