# JustAuth — Universal Third-Party Login Library for Java

> An out-of-the-box Java library for integrating social login from 30+ providers including GitHub, Google, Facebook, WeChat, and more with a unified API.

## Install

Save in your project root:

# JustAuth — Universal Third-Party Login Library for Java

## Quick Use
```xml
<dependency>
  <groupId>me.zhyd.oauth</groupId>
  <artifactId>JustAuth</artifactId>
  <version>1.16.7</version>
</dependency>
```
```java
AuthRequest authRequest = new AuthGithubRequest(AuthConfig.builder()
    .clientId("your-client-id")
    .clientSecret("your-client-secret")
    .redirectUri("https://yourapp.com/callback")
    .build());
String authorizeUrl = authRequest.authorize(AuthStateUtils.createState());
```

## Introduction
JustAuth removes the repetitive work of implementing OAuth login flows for multiple social providers. It normalizes the authorization code exchange and user profile retrieval across 30+ platforms behind a single, consistent Java interface.

## What JustAuth Does
- Implements OAuth 2.0 / OAuth 1.0a flows for 30+ identity providers
- Returns a unified AuthUser object regardless of the provider
- Handles state parameter generation, token exchange, and user info requests
- Supports providers like GitHub, Google, Facebook, Twitter, Apple, GitLab, and more
- Provides optional PKCE and custom scope configuration per provider

## Architecture Overview
JustAuth defines an AuthRequest interface with authorize() and login() methods. Each provider has a concrete implementation that encodes the platform-specific OAuth endpoints, scopes, and profile API. The library handles HTTP communication internally, parses provider-specific JSON responses, and maps them to a common AuthUser model with fields like uuid, username, avatar, and email.

## Self-Hosting & Configuration
- Add JustAuth as a Maven dependency to your Spring Boot or plain Java project
- Register OAuth apps on each provider and obtain client ID and secret
- Create an AuthConfig with clientId, clientSecret, and redirectUri
- Instantiate the provider-specific AuthRequest and call authorize()
- Handle the callback by calling login(AuthCallback) to receive the AuthUser

## Key Features
- Unified AuthUser model across all providers simplifies downstream logic
- State parameter management prevents CSRF attacks on the OAuth callback
- Custom HTTP client adapter for environments with specific proxy or TLS needs
- Extensible design allows adding custom OAuth providers via the SPI
- Zero Spring dependency; works in any Java application

## Comparison with Similar Tools
- **Spring Security OAuth2 Client** — deep Spring integration but more configuration; JustAuth is provider-focused and framework-agnostic
- **Passport.js** — Node.js strategy-based auth; JustAuth serves the same purpose in Java
- **Auth.js (NextAuth)** — JavaScript/TypeScript ecosystem; JustAuth targets JVM applications
- **Socialite (Laravel)** — PHP social login; JustAuth is the Java equivalent with broader provider coverage

## FAQ
**Q: Which social providers does JustAuth support?**
A: Over 30, including GitHub, Google, Facebook, Twitter, Apple, GitLab, Bitbucket, LinkedIn, Amazon, Slack, Discord, and several Chinese platforms.

**Q: Does JustAuth handle token refresh?**
A: Yes. Providers that support refresh tokens expose a refresh() method on their AuthRequest.

**Q: Can I add a provider not yet supported?**
A: Yes. Implement the AuthSource and AuthRequest interfaces to register a custom provider.

**Q: Does it work with Spring Boot auto-configuration?**
A: The community justauth-spring-boot-starter provides auto-configuration and YAML-based provider setup.

## Sources
- https://github.com/justauth/JustAuth
- https://www.justauth.cn

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Source: https://tokrepo.com/en/workflows/asset-1a624c2b
Author: AI Open Source