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

# Introduction to DingTalk Sign-in

> DingTalk Sign-in for mobile apps is a DingTalk OAuth 2.0 authorization sign-in system built on the OAuth 2.0 protocol standard.

DingTalk Sign-in for mobile apps is a DingTalk OAuth 2.0 authorization sign-in system built on the [OAuth 2.0 protocol standard](https://oauth.net/2/).

**Note**

* Currently, DingTalk Sign-in on mobile apps only supports the native sign-in method, which requires users to install the DingTalk Client-side.
* For Android apps, keep the DingTalk Sign-in button visible at all times. When a user's phone does not have the DingTalk Client-side installed, guide the user to download and install it.

## Use Case

When an employee uses an App developed in-house by their organization, they need to sign in with an account and password. To simplify sign-in, add a DingTalk button directly on the sign-in page so the employee can sign in to the App using their DingTalk account.

The image below shows the sign-in page of the BOC International client. Users who have a DingTalk account and have installed the DingTalk Client-side can sign in directly with DingTalk Authorization, without entering an account and password.

## Instructions

When your App needs to use DingTalk Sign-in, first add a DingTalk App on the **DingTalk Open Platform**, then integrate the authorization sign-in request using the SDK provided by the DingTalk Open Platform. After you integrate the SDK correctly and obtain the relevant authorization scope (the scope of authorization; currently, DingTalk only supports authorization sign-in and retrieving a user's basic information), the developer's mobile App launches the DingTalk App locally on the device for authorization sign-in. After the DingTalk user confirms, DingTalk launches the developer's mobile App and passes the temporary authorization ticket `code` parameter. Then, call the DingTalk personal user information API to retrieve the basic information of the signed-in user, including the phone number, DingTalk Name, DingTalk Profile Photo URL, and more.