Introduction

Sendbound is an email infrastructure platform. Use the REST API to send transactional email, manage contacts and segments, run campaigns, and configure sending domains — all from your own code.

Base URL

All API requests are made to:

https://api.sendbound.com/v1

Request format

The API accepts application/json request bodies and returns application/json responses. All requests must include the Content-Type: application/json header when sending a body.

Authentication

All endpoints require a secret API key passed as a Bearer token:

Authorization: Bearer sk_live_...

See Authentication for details on creating and managing API keys.

Response format

Successful responses return the requested resource directly. Errors return a structured object:

{
  "error": {
    "code": "invalid_recipient",
    "message": "The recipient email address is invalid.",
    "details": {}
  }
}

See Error Handling for the full list of error codes.

SDKs & libraries

Official SDKs are available for Node.js, Python, and Go. You can also use any HTTP client directly against the REST API. See SDKs & Libraries.

SMTP relay

In addition to the REST API, Sendbound exposes an SMTP relay on port 587. Authenticate with apikey as the username and your secret key as the password. See the Developer section of your dashboard for credentials.