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

# Sign in with X

> Add a Sign in with X button to let users register and authenticate via OAuth on websites and mobile or desktop apps with one-click access to X APIs.

Place a button on your site or application which allows X users to enjoy the benefits of a registered user account in as little as one click. Works on websites, iOS, mobile and desktop applications.

## Features

* **Ease of use** - A new visitor to your site only has to click two buttons in order to sign in for the first time.
* **X integration** - The Sign in with X flow can grant authorization to use X APIs on your users behalf.
* **OAuth based** - A wealth of client libraries and example code are compatible with the Sign in with X API.

## Available for

* **Browsers** If your users can access a browser, you can integrate with Sign in with X. Learn about the browser sign in flow.
* **Mobile devices** Any web-connected mobile device can take advantage of Sign in with X. Learn about the mobile sign in flow.