Auth0 Authentication

You are an expert in Auth0 authentication implementation. Follow these guidelines when working with Auth0 in any project.

Core Principles

• Always use HTTPS for all Auth0 communications and callbacks
• Store sensitive configuration (client secrets, API keys) in environment variables, never in code
• Implement proper error handling for all authentication flows
• Follow the principle of least privilege for scopes and permissions

Environment Variables

# Required Auth0 Configuration
AUTH0_DOMAIN=your-tenant.auth0.com
AUTH0_CLIENT_ID=your-client-id
AUTH0_CLIENT_SECRET=your-client-secret
AUTH0_AUDIENCE=your-api-audience
AUTH0_CALLBACK_URL=https://your-app.com/callback
AUTH0_LOGOUT_URL=https://your-app.com

Authentication Flows

Authorization Code Flow with PKCE (Recommended for SPAs and Native Apps)

Always use PKCE for public clients:

import { Auth0Client } from '@auth0/auth0-spa-js';

const auth0 = new Auth0Client({
  domain: process.env.AUTH0_DOMAIN,
  clientId: process.env.AUTH0_CLIENT_ID,
  authorizationParams: {
    redirect_uri: window.location.origin,
    audience: process.env.AUTH0_AUDIENCE,
  },
  cacheLocation: 'localstorage', // Use 'memory' for higher security
  useRefreshTokens: true,
});

Authorization Code Flow (Server-Side Applications)

// Express.js example
const { auth } = require('express-openid-connect');

app.use(
  auth({
    authRequired: false,
    auth0Logout: true,
    secret: process.env.AUTH0_SECRET,
    baseURL: process.env.BASE_URL,
    clientID: process.env.AUTH0_CLIENT_ID,
    issuerBaseURL: `https://${process.env.AUTH0_DOMAIN}`,
  })
);

Auth0 Actions Best Practices

Actions have replaced Rules. Follow these guidelines:

Action Structure

exports.onExecutePostLogin = async (event, api) => {
  // 1. Early returns for efficiency
  if (!event.user.email_verified) {
    api.access.deny('Please verify your email before logging in.');
    return;
  }

  // 2. Use secrets for sensitive data (configured in Auth0 Dashboard)
  const apiKey = event.secrets.EXTERNAL_API_KEY;

  // 3. Minimize external calls - they affect login latency
  // 4. Never log sensitive information
  console.log(`User logged in: ${event.user.user_id}`);

  // 5. Add custom claims sparingly
  api.idToken.setCustomClaim('https://myapp.com/roles', event.authorization?.roles || []);
  api.accessToken.setCustomClaim('https://myapp.com/roles', event.authorization?.roles || []);
};

Action Security Rules

• Store secrets in Action Secrets, never hardcode them
• Limit the data sent to external services - never send the entire event object
• Use short timeouts for external API calls (default 20-second limit)
• Implement proper error handling to avoid authentication failures

Token Management

Access Token Best Practices

// Always validate tokens server-side
const { auth, requiredScopes } = require('express-oauth2-jwt-bearer');

const checkJwt = auth({
  audience: process.env.AUTH0_AUDIENCE,
  issuerBaseURL: `https://${process.env.AUTH0_DOMAIN}/`,
  tokenSigningAlg: 'RS256',
});

// Require specific scopes
const checkScopes = requiredScopes('read:messages');

app.get('/api/private-scoped', checkJwt, checkScopes, (req, res) => {
  res.json({ message: 'Protected resource' });
});

Refresh Token Configuration

• Enable refresh token rotation
• Set appropriate token lifetimes (access tokens: 1 hour max, refresh tokens: based on risk)
• Implement automatic token refresh in your client

Security Best Practices

CSRF Protection

// State parameter is automatically handled by Auth0 SDKs
// For custom implementations, always validate the state parameter
const state = generateSecureRandomString();
sessionStorage.setItem('auth0_state', state);

Redirect URI Security

• Whitelist all redirect URIs in Auth0 Dashboard
• Use exact string matching for redirect URIs
• Never use wildcard redirect URIs in production

Session Management

// Implement session timeouts
const sessionConfig = {
  absoluteDuration: 86400, // 24 hours
  inactivityDuration: 3600, // 1 hour of inactivity
};

Multi-Factor Authentication

// Enforce MFA for sensitive operations
exports.onExecutePostLogin = async (event, api) => {
  // Check if MFA has been completed
  if (!event.authentication?.methods?.find(m => m.name === 'mfa')) {
    // Trigger MFA challenge
    api.authentication.challengeWithAny([
      { type: 'otp' },
      { type: 'push-notification' },
    ]);
  }
how to use auth0-authentication
CursorClaude CodeClineCodexWindsurfGooseGitHub CopilotVS CodeGemini CLIKiloOpencodeKimi CLIRoo ClineAiderContinueZedBolt.newLovablev0Replit AgentSweepSmol DeveloperDevinCavemanAmpAntigravity
How to use auth0-authentication on Cursor
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1
Prerequisites
Before installing skills in Cursor, ensure your development environment meets these requirements:
›Cursor installed and configured on your development machine
›Node.js version 16.0+ with npm package manager (verify with node --version)
›Active project directory or workspace where you want to add auth0-authentication
2
Execute installation command
Execute the skills CLI command in your project's root directory to begin installation:
$npx skills add https://github.com/mindrally/skills --skill auth0-authenticationcopy
The skills CLI fetches auth0-authentication from GitHub repository mindrally/skills and configures it for Cursor.
3
Select Cursor when prompted
The CLI will show a list of available agents. Use arrow keys to navigate and space to select Cursor:
◆ Which agents do you want to install to?
│
│ ── Universal (.agents/skills) ── always included ────
│   • Amp
│   • Antigravity
│   • Cline
│   • Codex
│ ●Cursor(selected)
│   • Cursor
│   • Windsurf
4
Verify installation
Confirm successful installation by checking the skill directory location:
.cursor/skills/auth0-authentication
Reload or restart Cursor to activate auth0-authentication. Access the skill through slash commands (e.g., /auth0-authentication) or your agent's skill management interface.
⚠
Security & Verification Notice
We perform automated surface-level scans (Gen AI Scanner, Socket, Snyk) during installation. These checks detect common vulnerabilities but do not guarantee complete security. Always review skill source code and verify the publisher's reputation before production use.
Skills execute code in your development environment. Always verify the publisher's identity, review recent commits, and test in isolated environments before production deployment.
Additional Resources
›View source code on GitHub›Skills CLI documentation›Learn more about Cursor›What are agent skills?