Auth0 Nuxt SDK

Overview

Server-side session authentication for Nuxt 3/4. NOT the same as @auth0/auth0-vue (client-side SPA).

Core principle: Uses server-side encrypted cookie sessions, not client-side tokens.

When to Use

Use this when:

• Building Nuxt 3/4 applications with server-side rendering (Node.js 20 LTS+)
• Need secure session management with encrypted cookies
• Protecting server routes and API endpoints
• Accessing Auth0 Management API or custom APIs

Don't use this when:

• Using Nuxt 2 (not supported - use different Auth0 SDK)
• Building pure client-side SPA without server (use @auth0/auth0-vue instead)
• Using non-Auth0 authentication provider
• Static site generation only (SSG) without server runtime

Critical Mistakes to Avoid

Mistake	Solution
Installing @auth0/auth0-vue or @auth0/auth0-spa-js	Use @auth0/auth0-nuxt
Auth0 app type "Single Page Application"	Use "Regular Web Application"
Env vars: VITE_AUTH0_* or VUE_APP_AUTH0_*	Use NUXT_AUTH0_* prefix
Using useUser() for security checks	Use useAuth0(event).getSession() server-side
Missing callback URLs in Auth0 Dashboard	Add http://localhost:3000/auth/callback
Weak/missing session secret	Generate: openssl rand -hex 64

Quick Setup

# 1. Install
npm install @auth0/auth0-nuxt

# 2. Generate secret
openssl rand -hex 64

# 3. .env
NUXT_AUTH0_DOMAIN=your-tenant.auth0.com
NUXT_AUTH0_CLIENT_ID=your-client-id
NUXT_AUTH0_CLIENT_SECRET=your-client-secret
NUXT_AUTH0_SESSION_SECRET=<from-openssl>
NUXT_AUTH0_APP_BASE_URL=http://localhost:3000
NUXT_AUTH0_AUDIENCE=https://your-api  # optional

// 4. nuxt.config.ts
export default defineNuxtConfig({
  modules: ['@auth0/auth0-nuxt'],
  runtimeConfig: {
    auth0: {
      domain: '',
      clientId: '',
      clientSecret: '',
      sessionSecret: '',
      appBaseUrl: 'http://localhost:3000',
      audience: '',  // optional
    },
  },
})

Built-in Routes

The SDK automatically mounts these routes:

Route	Method	Purpose
/auth/login	GET	Initiates login flow. Supports ?returnTo=/path parameter
/auth/callback	GET	Handles Auth0 callback after login
/auth/logout	GET	Logs user out and redirects to Auth0 logout
/auth/backchannel-logout	POST	Receives logout tokens for back-channel logout

Customize: Pass routes: { login, callback, logout, backchannelLogout } or mountRoutes: false to module config.

Composables

Composable	Context	Usage
useAuth0(event)	Server-side	Access getUser(), getSession(), getAccessToken(), logout()
useUser()	Client-side	Display user data only. Never use for security checks

// Server example
const auth0 = useAuth0(event);
const session = await auth0.getSession();

<script setup>
const user = useUser();
</script>

<template>
  <div v-if="user">Welcome {{ user.name }}</div>
<template>

Protecting Routes

Three layers: Route middleware (client), server middleware (SSR), API guards.

// middleware/auth.ts - Client navigation
export default defineNuxtRouteMiddleware((to) => {
  if (!useUser().value) return navigateTo(`/auth/login?returnTo=${encodeURIComponent(to.path)}`);
});

// server/middleware/auth.server.ts - SSR protection
export default defineEventHandler(async (event) => {
  const url = getRequestURL(event);
  const auth0Client = useAuth0(event);
  const session = await auth0Client.getSession();
  if (!session)  {
    return sendRedirect(event, `/auth/login?returnTo=${encodeURIComponent(url.pathname)}`);
  }
});

// server/api/protected.ts - API endpoint protection
export default defineEventHandler(async (event) => {
  const auth0Client = useAuth0(event);
  const session = await auth0Client.getSession();

  if (!session) {
    throw createError({
      statusCode: 401,
      statusMessage: 'Unauthorized'
    });
  }

  return { data: 'protected data' };
});

For role-based, permission-based, and advanced patterns: route-protection.md

Session Management

Stateless (Default)

Uses encrypted, chunked cookies. No configuration needed.

Stateful (Redis, MongoDB, etc.)

For larger sessions or distributed systems:

// nuxt.config.ts
modules: [
  ['@auth0/auth0-nuxt', {
    sessionStoreFactoryPath: '~/server/utils/session-store-factory.ts'
  }]
]

For complete session store implementations, see: session-stores.md

API Integration

Configure audience for API access tokens:

// nuxt.config.ts
runtimeConfig: {
  auth0: {
    audience: 'https://your-api-identifier',
  }
}

Retrieve tokens server-side:

// server/api/call-api.ts
export default defineEventHandler(async (event) => {
  const auth0Client = useAuth0(event);
  const { accessToken } = await auth0Client.getAccessToken();

  return await $fetch('https://api.example.com/data', {
    headers: {
      Authorization: `Bearer ${accessToken}`
    }
  });
});

Security Checklist

• ✅ Server-side validation only (never trust useUser())
• ✅ HTTPS in production
• ✅ Strong session secret (openssl rand -hex 64)
• ✅ Never commit .env files
• ✅ Stateful sessions for PII/large data

Troubleshooting

Error	Solution
"Module not found"	Install @auth0/auth0-nuxt, not @auth0/auth0-vue
"Missing domain/clientId/clientSecret"	Check NUXT_AUTH0_ prefix, .env location, runtimeConfig
"Redirect URI mismatch"	Match Auth0 Dashboard callback to appBaseUrl + /auth/callback
"useAuth0 is not defined"	Use only in server context with H3 event object
Cookies too large	Use stateful sessions or reduce scopes

Additional Resources

Guides: Route Protection Patterns • Custom Session Stores • Common Examples

Links: Auth0-Nuxt GitHub • Auth0 Docs • Nuxt Modules