> ## Documentation Index
> Fetch the complete documentation index at: https://docs.getmany.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Understand general concepts, response codes, and authentication strategies.

## Base URL

The Resend 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:

```
https://api.getmany.io
```

## Authentication

To authenticate you need to add an *Authorization* header with the contents of the header being `Bearer gm_xxxxxxxxx` where `gm_xxxxxxxxx` is your [API Key](https://app.getmany.io/integrations/api).

```
Authorization: Bearer gm_xxxxxxxxx
```

## Response codes

Resend 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.            |
| `403`  | The API key used was invalid.            |
| `404`  | The resource was not found.              |
| `429`  | The rate limit was exceeded.             |
| `5xx`  | Indicates an error with Getmany servers. |

## Rate limit

The default maximum rate limit is **20 requests per minute**. This number can be increased for trusted senders by request. After that, you'll hit the rate limit and receive a `429` response error code.