Stack Auth vs Clerk vs Auth.js: Best Auth for Next.js (2026)
Authentication in Next.js has a new contender. Stack Auth is an open-source, self-hostable auth platform that aims to combine Clerk's DX with Auth.js's flexibility. Here's how it compares.
Quick Comparison
| Feature | Stack Auth | Clerk | Auth.js |
|---|---|---|---|
| Type | Open-source + hosted | Managed SaaS | Open-source library |
| Self-host | Yes (Docker) | No | N/A (library) |
| Pre-built UI | Yes (components) | Yes (excellent) | No |
| Email/password | Yes | Yes | Via credentials |
| OAuth providers | 20+ | 20+ | 80+ |
| MFA | Yes | Yes | Limited |
| Organizations | Yes | Yes (paid) | No |
| User management UI | Yes (dashboard) | Yes (dashboard) | No |
| Webhooks | Yes | Yes | No |
| Free tier | Unlimited (self-host) | 10K MAUs | Free (library) |
| Pricing | Free or hosted plans | From $25/mo + MAU | Free |
Stack Auth: Open-Source Clerk Alternative
Stack Auth launched as an open-source alternative to Clerk with a similar component-based approach.
Strengths
- Open-source (MIT). Full source code, self-host for free, no vendor lock-in
- Drop-in components.
<SignIn />,<SignUp />,<UserButton />— similar to Clerk's DX - Self-hostable. Docker deployment with PostgreSQL. Control your auth data
- Organizations built-in. Multi-tenant support included in the free/open-source version (Clerk charges for this)
- User management dashboard. Admin panel for managing users, similar to Clerk's dashboard
- Server and client hooks. Works with Next.js App Router, Server Components, and middleware
Weaknesses
- Newer project. Less battle-tested than Clerk or Auth.js
- Smaller community. Fewer tutorials, examples, and Stack Overflow answers
- Fewer OAuth providers than Auth.js (20+ vs 80+)
- Self-hosting requires ops. Docker, PostgreSQL, maintenance
- Less polished components than Clerk's UI
Best For
Teams who want Clerk-like DX with open-source flexibility and self-hosting capability. Startups who want organizations/multi-tenancy without Clerk's Enterprise pricing.
Clerk: Polish and Speed
Clerk remains the most polished auth solution for Next.js.
Strengths
- Best-in-class UI components and customization
- Fastest time-to-implementation
- Excellent documentation and community
- Multi-session support
- Managed infrastructure (zero ops)
Weaknesses
- Closed source, vendor lock-in
- SSO/organizations require Enterprise plan
- Per-MAU pricing adds up
- No self-hosting
Best For
Teams that want the best DX and don't mind paying for managed auth.
Auth.js: Maximum Flexibility
Auth.js (NextAuth) gives you building blocks, not a complete solution.
Strengths
- 80+ OAuth providers
- JWT or database sessions
- Complete control over everything
- Zero cost, no vendor dependency
- Largest community
Weaknesses
- No pre-built UI (build your own)
- No user management dashboard
- No organizations/multi-tenancy
- Email/password is second-class
- Configuration complexity
Best For
Developers who want full control and primarily need OAuth/social login.
Decision Matrix
| Priority | Choose |
|---|---|
| Fastest implementation | Clerk |
| Open-source + components | Stack Auth |
| Maximum OAuth providers | Auth.js |
| Self-hosting required | Stack Auth |
| Organizations (free) | Stack Auth |
| Organizations (managed) | Clerk |
| Smallest bundle | Auth.js |
| Best documentation | Clerk |
FAQ
Is Stack Auth production-ready?
Yes, with caveats. It's being used in production but is significantly newer than Clerk (7+ years) or Auth.js (4+ years). Evaluate the current issue tracker and release frequency before committing.
Can I migrate from Clerk to Stack Auth?
Yes, both use similar component patterns. User data migration requires export/import. The component API is similar enough that migration is manageable.
Which is cheapest for a SaaS with 50K users?
Stack Auth (self-hosted): $0 + ~$20/mo hosting. Auth.js: $0. Clerk: ~$825/mo ($25 base + $0.02 × 40K overage users).
The Verdict
- Stack Auth if you want open-source Clerk with self-hosting and free organizations
- Clerk if you want the best DX and managed everything
- Auth.js if you want maximum flexibility and OAuth provider coverage
Stack Auth is the most exciting newcomer in the auth space. For cost-conscious startups needing multi-tenancy, it's a compelling Clerk alternative.