Base URL
The Unosend API is built on REST principles. We enforce HTTPS in every request to improve data security, integrity, and privacy. The API does not support HTTP. All requests contain the following base URL:Authentication
To authenticate you need to add anAuthorization header with the contents of the header being Bearer un_xxxxxxxxxx where un_xxxxxxxxxx is your API Key.
Response codes
Unosend uses standard HTTP codes to indicate the success or failure of your requests. In general,2xx HTTP codes correspond to success, 4xx codes are for user-related failures, and 5xx codes are for infrastructure issues.
| Status | Description |
|---|---|
200 | Successful request. |
400 | Check that the parameters were correct. |
401 | The API key used was missing or invalid. |
403 | The API key doesn’t have permissions for the request. |
404 | The requested resource was not found. |
422 | Unprocessable entity. Check the request body. |
429 | The rate limit was exceeded. |
500 | Internal server error. |
Rate limit
The API has a rate limit of 100 requests per second. If you exceed this limit, you’ll receive a429 response.
Rate limit headers are included in all responses:
| Header | Description |
|---|---|
X-RateLimit-Limit | Maximum requests per window |
X-RateLimit-Remaining | Requests remaining in current window |
X-RateLimit-Reset | Unix timestamp when the window resets |
Pagination
List endpoints support pagination usinglimit and offset query parameters:
| Parameter | Type | Default | Description |
|---|---|---|---|
limit | integer | 20 | Number of items per page (max 100) |
offset | integer | 0 | Number of items to skip |
FAQ
What's the difference between un_ and re_ API keys?
What's the difference between un_ and re_ API keys?
Unosend API keys start with
un_ prefix for easy identification. If you’re migrating from Resend, you’ll need to generate new API keys in the Unosend dashboard.Can I use the API from the browser?
Can I use the API from the browser?
No, API requests should only be made from your server to keep your API key secure. Never expose your API key in client-side code.
What's the maximum email size?
What's the maximum email size?
The maximum total email size including attachments is 40MB.