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OpenSend docs

Introduction

Core concepts for the OpenSend API.

Raw markdown

OpenSend is a REST API for sending, receiving, and operating email on infrastructure you control. You can use OpenSend Cloud at https://opensend.namuh.co or run the same API surface on your own deployment.

Base URL

txt
https://opensend.namuh.co

For local development, use the port configured by your app, usually:

txt
http://localhost:3015

Authentication

Use an OpenSend API key in the Authorization header.

http
Authorization: Bearer os_YOUR_API_KEY

Dashboard session cookies are not API credentials. Create API keys from the dashboard or API key endpoints, scope them narrowly, and rotate keys when they leave your control.

First production send

A production send needs three things:

  1. An os_ API key.
  2. A verified sending domain.
  3. A request to /emails, /emails/batch, a broadcast send route, or an SDK method that calls those APIs.

Use idempotency keys for retryable send requests so duplicate network retries replay the original accepted response instead of creating extra sends.

Response codes

  • 200 / 201 / 202 — request accepted or completed.
  • 400 — malformed request or invalid state.
  • 401 — missing API key.
  • 403 — API key lacks the required permission.
  • 404 — resource not found for the authenticated tenant.
  • 409 — idempotency or conflict error.
  • 422 — validation error.
  • 429 — rate limit exceeded.
  • 500 — server error.

Machine-readable contracts

  • OpenAPI: /openapi.json
  • LLM docs index: /docs/llms.txt
  • Styled human docs: /docs