auth0-react

SKILL.md

Auth0 React Integration

Add authentication to React single-page applications using @auth0/auth0-react.

Prerequisites

React 16.11+ application (Vite or Create React App) - supports React 16, 17, 18, and 19

Auth0 account and application configured

If you don't have Auth0 set up yet, use the auth0-quickstart skill first

When NOT to Use

Next.js applications - Use auth0-nextjs skill for both App Router and Pages Router

React Native mobile apps - Use auth0-react-native skill for iOS/Android

Server-side rendered React - Use framework-specific SDK (Next.js, Remix, etc.)

Embedded login - This SDK uses Auth0 Universal Login (redirect-based)

Backend API authentication - Use express-openid-connect or JWT validation instead

Quick Start Workflow

1. Install SDK

npm install @auth0/auth0-react

2. Configure Environment

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

For manual setup:

Create .env file:

Vite:

VITE_AUTH0_DOMAIN=your-tenant.auth0.com
VITE_AUTH0_CLIENT_ID=your-client-id

Create React App:

REACT_APP_AUTH0_DOMAIN=your-tenant.auth0.com
REACT_APP_AUTH0_CLIENT_ID=your-client-id

3. Wrap App with Auth0Provider

Update src/main.tsx (Vite) or src/index.tsx (CRA):

import React from 'react';
import ReactDOM from 'react-dom/client';
import { Auth0Provider } from '@auth0/auth0-react';
import App from './App';

ReactDOM.createRoot(document.getElementById('root')!).render(
  <React.StrictMode>
    <Auth0Provider
      domain={import.meta.env.VITE_AUTH0_DOMAIN} // or process.env.REACT_APP_AUTH0_DOMAIN
      clientId={import.meta.env.VITE_AUTH0_CLIENT_ID}
      authorizationParams={{
        redirect_uri: window.location.origin
      }}
    >
      <App />
    </Auth0Provider>
  </React.StrictMode>
);

4. Add Authentication UI

import { useAuth0 } from '@auth0/auth0-react';

export function LoginButton() {
  const { loginWithRedirect, logout, isAuthenticated, user, isLoading } = useAuth0();

  if (isLoading) return <div>Loading...</div>;

  if (isAuthenticated) {
    return (
      <div>
        <span>Welcome, {user?.name}</span>
        <button onClick={() => logout({ logoutParams: { returnTo: window.location.origin } })}>
          Logout
        </button>
      </div>
    );
  }

  return <button onClick={() => loginWithRedirect()}>Login</button>;
}

5. Test Authentication

Start your dev server and test the login flow:

npm run dev  # Vite
# or
npm start    # CRA

Detailed Documentation

Setup Guide - Automated setup scripts (Bash/PowerShell), CLI commands, manual configuration

Integration Guide - Protected routes, API calls, error handling, advanced patterns

API Reference - Complete SDK API, configuration options, hooks reference, testing strategies

Common Mistakes

Mistake
Fix

Forgot to add redirect URI in Auth0 Dashboard
Add your application URL (e.g., http://localhost:3000, https://app.example.com) to Allowed Callback URLs in Auth0 Dashboard

Using wrong env var prefix
Vite uses VITE_ prefix, Create React App uses REACT_APP_

Not handling loading state
Always check isLoading before rendering auth-dependent UI

Storing tokens in localStorage
Never manually store tokens - SDK handles secure storage automatically

Missing Auth0Provider wrapper
Entire app must be wrapped in <Auth0Provider>

Provider not at root level
Auth0Provider must wrap all components that use auth hooks

Wrong import path for env vars
Vite uses import.meta.env.VITE_*, CRA uses process.env.REACT_APP_*

Using acr_values redirect for in-app MFA
Use useAuth0().mfa API for in-app enrollment/challenge/verify flows

Not catching MfaRequiredError
Wrap getAccessTokenSilently in try/catch and check instanceof MfaRequiredError

Making direct HTTP calls to MFA endpoints
Use the mfa property from useAuth0() — it handles token management automatically

Forgetting refresh tokens for step-up MFA
Set useRefreshTokens={true} on Auth0Provider when using interactiveErrorHandler="popup"

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

Core Hooks:

useAuth0() - Main authentication hook

isAuthenticated - Check if user is logged in

user - User profile information

loginWithRedirect() - Initiate login

logout() - Log out user

getAccessTokenSilently() - Get access token for API calls

mfa - MFA API client for enrollment, challenge, and verification

mfa.getAuthenticators(mfaToken) - List enrolled authenticators

mfa.getEnrollmentFactors(mfaToken) - Get available enrollment factors

mfa.enroll(params) - Enroll new authenticator (OTP, SMS, Email, Voice, Push)

mfa.challenge(params) - Initiate MFA challenge

mfa.verify(params) - Verify MFA challenge and complete authentication

MFA Error Types (import from @auth0/auth0-react):

MfaRequiredError - Thrown by getAccessTokenSilently when MFA is needed (has mfa_token and mfa_requirements)

MfaEnrollmentError, MfaChallengeError, MfaVerifyError - Thrown by respective mfa.* methods

Common Use Cases:

Login/Logout buttons → See Step 4 above

Protected routes → Integration Guide

API calls with tokens → Integration Guide

Error handling → Integration Guide

MFA handling → Integration Guide

References

Auth0 React SDK Documentation

Auth0 React Quickstart

SDK GitHub Repository