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

# Introduction

> Fundamental concepts of Usend's API.

## Base URL

useSend's API is built on REST principles and is served over HTTPS. To ensure data privacy, unencrypted HTTP is not supported.

The Base URL for all API endpoints is:

```sh Terminal theme={null}
https://app.usesend.com/api/
```

## Authentication

Authentication to Usend's API is performed via the Authorization header with a Bearer token. To authenticate, you need to include the Authorization header with the word Bearer followed by your token in your API requests like so:

```sh Terminal theme={null}
Authorization: Bearer us_12345
```

You can create a new token/API key under your useSend [Developer Settings](https://app.usesend.com/dev-settings/api-keys).