NextAuth.js (Auth.js)
Open-source authentication library for Next.js and other frameworks (SvelteKit, SolidStart, Express). Provides OAuth/OIDC integration with 50+ providers (Google, GitHub, Discord, etc.), magic links, credentials auth, and JWT/database sessions. Auth.js v5 is the framework-agnostic rewrite of NextAuth.js v4 — works in Edge Runtime, server components, and all modern JS frameworks. The most popular Next.js authentication solution.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
CSRF protection built-in. Secure cookie handling. JWT or database sessions. AUTH_SECRET required for session signing. Active security disclosures handled. ISC open source and auditable.
⚡ Reliability
Best When
You're building a Next.js application and want the most popular, well-documented OAuth + session authentication solution with 50+ providers.
Avoid When
You need SAML SSO, fine-grained RBAC, or are on a non-JavaScript backend — use Auth0, Keycloak, or backend-specific auth libraries.
Use Cases
- • Add OAuth authentication (Google, GitHub, Discord) to Next.js applications with minimal configuration using built-in providers
- • Implement JWT or database sessions in Next.js with server components (App Router) using Auth.js v5's edge-compatible design
- • Build magic link (email) authentication flows using Auth.js's Resend, Nodemailer, or SendGrid adapters
- • Protect API routes and server components by checking session in Next.js middleware using Auth.js helpers
- • Add multi-provider authentication to SvelteKit, SolidStart, or Express applications using the Auth.js universal adapter
Not For
- • Non-Node.js backends — Auth.js is JavaScript/TypeScript only; use Authlib (Python) or omniauth (Ruby) for other languages
- • Enterprise SSO with SAML — Auth.js supports OIDC but SAML requires additional libraries or a provider like Auth0/Okta
- • Applications needing fine-grained RBAC — Auth.js provides authentication, not authorization; combine with Casbin or custom middleware
Interface
Authentication
Library that implements OAuth 2.0/OIDC. Generates sessions (JWT or database). Credentials provider for username/password. Email provider for magic links. AUTH_SECRET environment variable required.
Pricing
ISC licensed. Completely free. Most popular open-source auth for Next.js.
Agent Metadata
Known Gotchas
- ⚠ Auth.js v5 (authjs.dev) has breaking changes from NextAuth.js v4 — migration guide required; v4 config structure doesn't work in v5
- ⚠ AUTH_SECRET must be set in environment — missing secret causes cryptic errors; generate with 'npx auth secret'
- ⚠ App Router (Next.js 13+) requires different session access patterns than Pages Router — use auth() function instead of getServerSession()
- ⚠ Database adapter is required for email (magic link) auth — JWT sessions can't store verification tokens without a database
- ⚠ OAuth callback URLs must be registered in each provider's console — missing callback URL registration causes OAuth errors
- ⚠ Edge Runtime (Middleware) session access uses a different import than server components — import from 'next-auth' vs edge-specific import
Alternatives
Full Evaluation Report
Detailed scoring breakdown, competitive positioning, security analysis, and improvement recommendations for NextAuth.js (Auth.js).
Scores are editorial opinions as of 2026-03-06.