Auth0 Express Integration

Add authentication to Express.js web applications using express-openid-connect.

Prerequisites

• Express.js application
• Auth0 account and application configured
• If you don't have Auth0 set up yet, use the auth0-quickstart skill first

When NOT to Use

• Single Page Applications - Use auth0-react, auth0-vue, or auth0-angular for client-side auth
• Next.js applications - Use auth0-nextjs skill which handles both client and server
• Mobile applications - Use auth0-react-native for React Native/Expo
• Stateless APIs - Use JWT validation middleware instead of session-based auth
• Microservices - Use JWT validation for service-to-service auth

Quick Start Workflow

1. Install SDK

npm install express-openid-connect dotenv

2. Configure Environment

For automated setup with Auth0 CLI, see Setup Guide for complete scripts.

For manual setup:

Create .env:

SECRET=<openssl-rand-hex-32>
BASE_URL=http://localhost:3000
CLIENT_ID=your-client-id
CLIENT_SECRET=your-client-secret
ISSUER_BASE_URL=https://your-tenant.auth0.com
AUDIENCE=https://your-api-identifier  # only required if calling external APIs (Step 3a)

Generate secret: openssl rand -hex 32

3. Configure Auth Middleware

Update your Express app (app.js or index.js):

require('dotenv').config();
const express = require('express');
const { auth, requiresAuth } = require('express-openid-connect');

const app = express();

// Configure Auth0 middleware
app.use(auth({
  authRequired: false,  // Don't require auth for all routes
  auth0Logout: true,    // Enable logout endpoint
  secret: process.env.SECRET,
  baseURL: process.env.BASE_URL,
  clientID: process.env.CLIENT_ID,
  issuerBaseURL: process.env.ISSUER_BASE_URL,
  clientSecret: process.env.CLIENT_SECRET
}));

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

Calling external APIs? If you need an access token for a downstream API, you must add authorizationParams — see Step 3a below.

This automatically creates:

• /login - Login endpoint
• /logout - Logout endpoint
• /callback - OAuth callback

3a. Configure Middleware for API Access (when calling external APIs)

When you need an access token for an external API, audience must go inside authorizationParams — putting it at the top level is silently ignored and no access token is issued.

// SDK auto-loads SECRET, BASE_URL, CLIENT_ID, ISSUER_BASE_URL, CLIENT_SECRET from env vars
app.use(auth({
  authRequired: false,
  auth0Logout: true,
  authorizationParams: {            // ← required for access tokens
    response_type: 'code',          // ← required: authorization code flow
    audience: process.env.AUDIENCE, // ← API identifier (never top-level)
    scope: 'openid profile email'
  }
}));

Then access the token in your route:

app.get('/api-call', requiresAuth(), async (req, res) => {
  const { access_token } = req.oidc.accessToken; // object, not a string
  const response = await fetch('https://your-api.com/data', {
    headers: { Authorization: `Bearer ${access_token}` }
  });
  res.json(await response.json());
});

4. Add Routes

// Public route
app.get('/', (req, res) => {
  res.send(req.oidc.isAuthenticated() ? 'Logged in' : 'Logged out');
});

// Protected route
app.get('/profile', requiresAuth(), (req, res) => {
  res.send(`
    <h1>Profile</h1>
    <p>Name: ${req.oidc.user.name}</p>
    <p>Email: ${req.oidc.user.email}</p>
    <pre>${JSON.stringify(req.oidc.user, null, 2)}</pre>
    <a href="/logout">Logout</a>
  `);
});

// Login/logout links
app.get('/', (req, res) => {
  res.send(`
    ${req.oidc.isAuthenticated() ? `
      <p>Welcome, ${req.oidc.user.name}!</p>
      <a href="/profile">Profile</a>
      <a href="/logout">Logout</a>
    ` : `
      <a href="/login">Login</a>
    `}
  `);
});

5. Test Authentication

Start your server:

node app.js

Visit http://localhost:3000 and test the login flow.

Detailed Documentation

• Setup Guide - Automated setup scripts, environment configuration, Auth0 CLI usage
• Integration Guide - Protected routes, sessions, API integration, error handling
• API Reference - Complete middleware API, configuration options, request properties

Common Mistakes

Related Skills

• auth0-quickstart - Basic Auth0 setup
• auth0-migration - Migrate from another auth provider
• auth0-mfa - Add Multi-Factor Authentication
• auth0-cli - Manage Auth0 resources from the terminal

Quick Reference

Middleware Options:

• authRequired - Require auth for all routes (default: false)
• auth0Logout - Enable /logout endpoint (default: false)
• secret - Session secret (required)
• baseURL - Application URL (required)
• clientID - Auth0 client ID (required)
• issuerBaseURL - Auth0 tenant URL (required)

Request Properties:

• req.oidc.isAuthenticated() - Check if user is logged in
• req.oidc.user - User profile object
• req.oidc.accessToken - Access token object ({ access_token, token_type, expires_in }); expires_in is seconds remaining. Destructure with const { access_token } = req.oidc.accessToken. Also exposes isExpired() and refresh() methods. Only populated when authorizationParams with audience + response_type: 'code' is configured
• req.oidc.idToken - ID token
• req.oidc.refreshToken - Refresh token

Common Use Cases:

• Protected routes → Use requiresAuth() middleware (see Step 4)
• Check auth status → req.oidc.isAuthenticated()
• Get user info → req.oidc.user
• Call APIs → Integration Guide

References

• Express OpenID Connect Documentation
• Auth0 Express Quickstart
• SDK GitHub Repository