---
name: oauth-implementation
description: >
  Implement secure OAuth 2.0, OpenID Connect (OIDC), JWT authentication, and SSO
  integration. Use when building secure authentication systems for web and
  mobile applications.
---

# OAuth Implementation

## Table of Contents

- [Overview](#overview)
- [When to Use](#when-to-use)
- [Quick Start](#quick-start)
- [Reference Guides](#reference-guides)
- [Best Practices](#best-practices)

## Overview

Implement industry-standard OAuth 2.0 and OpenID Connect authentication flows with JWT tokens, refresh tokens, and secure session management.

## When to Use

- User authentication systems
- Third-party API integration
- Single Sign-On (SSO) implementation
- Mobile app authentication
- Microservices security
- Social login integration

## Quick Start

Minimal working example:

```javascript
// oauth-server.js - Complete OAuth 2.0 implementation
const express = require("express");
const jwt = require("jsonwebtoken");
const crypto = require("crypto");
const bcrypt = require("bcrypt");

class OAuthServer {
  constructor() {
    this.app = express();
    this.clients = new Map();
    this.authorizationCodes = new Map();
    this.refreshTokens = new Map();
    this.accessTokens = new Map();

    // JWT signing keys
    this.privateKey = process.env.JWT_PRIVATE_KEY;
    this.publicKey = process.env.JWT_PUBLIC_KEY;

    this.setupRoutes();
  }

  // Register OAuth client
  registerClient(clientId, clientSecret, redirectUris) {
    this.clients.set(clientId, {
      clientSecret: bcrypt.hashSync(clientSecret, 10),
// ... (see reference guides for full implementation)
```

## Reference Guides

Detailed implementations in the `references/` directory:

| Guide | Contents |
|---|---|
| [Node.js OAuth 2.0 Server](references/nodejs-oauth-20-server.md) | Node.js OAuth 2.0 Server |
| [Python OpenID Connect Implementation](references/python-openid-connect-implementation.md) | Python OpenID Connect Implementation |
| [Java Spring Security OAuth](references/java-spring-security-oauth.md) | Java Spring Security OAuth |

## Best Practices

### ✅ DO

- Use PKCE for public clients
- Implement token rotation
- Store tokens securely
- Use HTTPS everywhere
- Validate redirect URIs
- Implement rate limiting
- Use short-lived access tokens
- Log authentication events

### ❌ DON'T

- Store tokens in localStorage
- Use implicit flow
- Skip state parameter
- Expose client secrets
- Allow open redirects
- Use weak signing keys