Choosing between Clerk vs Auth0 vs Supabase Auth is one of the first real decisions a vibe coder faces when building anything with user accounts. Authentication is the foundation your entire app sits on, and switching later is painful. Pick the wrong provider and you are either overpaying at 1,000 users or rewriting your auth layer at 10,000.
This comparison is written for indie hackers and solo builders using AI coding tools to ship fast. We are looking at three things: how quickly you can integrate each option, what it costs as you grow, and which one fits your specific situation.
Why You Should Never Build Auth Yourself
Before comparing third-party options, let's address the temptation. Your AI coding assistant can generate a login form with password hashing in 30 seconds. It looks like auth. It is not auth.
Real authentication includes:
- Password hashing with proper algorithms (bcrypt, scrypt, argon2)
- Session management with secure, httpOnly cookies
- CSRF protection
- Rate limiting on login attempts
- Email verification flows
- Password reset flows
- OAuth integration (Google, GitHub, Apple sign-in)
- Multi-factor authentication
- Token rotation and refresh logic
- Compliance with data protection regulations
Building all of this correctly takes weeks of experienced security engineering. One mistake — storing passwords in plain text, using predictable session tokens, forgetting rate limiting — and you have a data breach. For an indie hacker, the risk-reward calculation is simple: use a service. The cost of a breach (legal, reputational, emotional) dwarfs any subscription fee.
Understanding MAU-Based Pricing
All three services charge based on Monthly Active Users (MAUs). An MAU is a unique user who authenticates at least once during a billing month. This pricing model means your auth costs scale directly with your user base, which is both fair and potentially alarming as you grow.
Key concepts:
- MAU counts unique users, not sessions. One user logging in 50 times counts as 1 MAU.
- Free tier MAUs are the users you do not pay for. Exceeding this triggers per-user charges.
- Social logins (Google, GitHub) count the same as email/password logins.
- Bot signups count as MAUs too, so you need CAPTCHA or bot protection to avoid paying for fake users.
The Three Contenders at a Glance
| Feature | Clerk | Supabase Auth | Auth0 |
|---|---|---|---|
| Free tier | 10,000 MAUs | 50,000 MAUs (unlimited on self-hosted) | 7,500 MAUs |
| Best framework integration | Next.js, React | Any (framework-agnostic) | Any (SDKs for everything) |
| Pre-built UI components | Yes, excellent | Basic (Auth UI library) | Universal Login (customizable) |
| Social logins | 20+ providers | 15+ providers | 30+ providers |
| MFA | Yes (all plans) | Yes (TOTP) | Yes (all plans) |
| Setup time | ~15 minutes | ~30 minutes | ~45 minutes |
| Self-hostable | No | Yes | No |
Pricing Comparison: 1K, 10K, and 100K MAUs
This is where the decision gets real. Auth pricing can range from free to hundreds of dollars per month depending on your user count.
| MAUs | Clerk | Supabase Auth | Auth0 |
|---|---|---|---|
| 1,000 | $0 | $0 | $0 |
| 10,000 | $0 | $0 (included with Supabase Pro at $25/mo) | $0 |
| 25,000 | $25 + $0.02/MAU over 10K = ~$325 | $25 (Supabase Pro, auth included) | $23/month (Essential plan) |
| 50,000 | ~$825 | $25 (still included) | $240/month (Essential plan) |
| 100,000 | ~$1,825 | $25 (still included) | Custom pricing |
The numbers tell a clear story at scale: Supabase Auth is dramatically cheaper because authentication is bundled with your database subscription. You pay $25/month for Supabase Pro and get auth for up to 100K+ users as part of the package. Clerk and Auth0 charge per MAU beyond their free tiers, which gets expensive fast.
But cost is not the only factor. Let's look at what each service does best.
Clerk: Fastest Integration for Next.js
Clerk was built from the ground up for React and Next.js applications. If you are building a Next.js app with Cursor or another AI coding tool, Clerk offers the smoothest integration experience available.
What makes Clerk special:
- Pre-built components that actually look good. Drop in
<SignIn />and<UserButton />and you have a complete auth UI in minutes. - Middleware-first approach for Next.js. Protecting routes is a few lines of configuration, not custom logic.
- Organization/team support built in. If your SaaS needs multi-tenant workspaces, Clerk handles this without additional libraries.
- Webhook integration for syncing user data with your database.
The trade-off: Clerk is expensive at scale. Once you pass 10,000 MAUs, you are paying $0.02 per additional user per month. At 50K users, that is $800/month just for authentication. For a bootstrapped indie hacker, that is a significant percentage of revenue.
Best for: Next.js projects where speed of integration matters most, and where you expect to stay under 10K MAUs for a while. Also strong for B2B SaaS that needs organization management.
Supabase Auth: Best Free Tier and Best Value at Scale
If you are already using Supabase for your database (and many vibe coders are), Supabase Auth is the obvious choice. Authentication is included with every Supabase project at no additional cost.
What makes Supabase Auth special:
- Included with Supabase. You are not paying for a separate auth service. Auth, database, storage, and edge functions are one package.
- Row Level Security (RLS) integration. Your auth system talks directly to your database's security policies. This is powerful and unique to Supabase.
- 50,000 free MAUs on the cloud-hosted version. Self-hosted has no MAU limit at all.
- Open source. You can inspect the code, self-host the entire stack, and are never locked in.
The trade-off: Supabase Auth's pre-built UI components are less polished than Clerk's. The Auth UI library exists, but you will likely customize it. Integration takes slightly longer, especially if you want a highly branded login experience. Documentation can be uneven for edge cases.
Best for: Any project already on Supabase, cost-conscious builders at any scale, and projects where database-level security (RLS) matters.
Auth0: The Enterprise Standard
Auth0 (owned by Okta) is the oldest and most feature-complete option. It supports every authentication scenario imaginable, from simple email/password to SAML-based enterprise SSO.
What makes Auth0 special:
- Enterprise SSO out of the box. If your customers need to sign in with their company's Okta, Azure AD, or Google Workspace, Auth0 is the standard choice.
- Universal Login provides a hosted login page that handles all auth flows. Reduces your security surface area.
- Actions and Hooks let you customize authentication flows with serverless functions (add custom claims, block certain logins, trigger workflows).
- Compliance certifications (SOC 2, HIPAA, GDPR) that enterprise customers require.
The trade-off: Auth0 is built for enterprise. The dashboard is powerful but complex. Setup takes longer than Clerk or Supabase Auth. The pricing is opaque at higher tiers (custom quotes). And the developer experience, while good, is not optimized for the "ship in a weekend" speed that vibe coders want.
Best for: B2B SaaS products that need enterprise SSO, projects requiring compliance certifications, and teams that prioritize proven reliability over developer experience.
The Free Alternative: Auth.js (NextAuth)
If you want to pay nothing and maintain full control, Auth.js (formerly NextAuth.js) is the developer-first alternative. It is an open-source library, not a service. You run it yourself, store sessions in your own database, and never pay per MAU.
What you get:
- Free forever, no MAU limits
- Support for 80+ OAuth providers
- Database adapters for Prisma, Drizzle, Supabase, and more
- Full control over the auth flow and UI
What you give up:
- No pre-built UI components (you build the login forms)
- No managed infrastructure (you handle session storage, token rotation)
- Security is your responsibility (keep the library updated, configure correctly)
- More complex setup, especially for features like MFA
Auth.js is excellent for developers who understand authentication concepts and want zero ongoing cost. For vibe coders who are new to auth, a managed service is safer.
Recommendation Matrix
Here is the straightforward recommendation based on your situation:
| If you are... | Use this | Why |
|---|---|---|
| Building a Next.js app and want to ship this weekend | Clerk | Fastest integration, best DX for React/Next.js |
| Already using Supabase for your database | Supabase Auth | Free, integrated, and scales without cost surprises |
| Cost-conscious and planning for 10K+ users | Supabase Auth | Best value at every scale above free tiers |
| Building B2B SaaS where customers need enterprise SSO | Auth0 | Industry standard for enterprise auth requirements |
| A developer who wants zero cost and full control | Auth.js | Free, open-source, no vendor dependency |
| Not sure yet and just want to start building | Supabase Auth | Lowest risk: free, generous limits, and easy to migrate away from |
The Bottom Line
For most indie hackers and vibe coders, Supabase Auth is the default recommendation. It is free at meaningful scale, integrates with the database you are likely already using, and does not surprise you with per-MAU charges as you grow.
Clerk wins on developer experience for Next.js projects, and it is worth the premium if you are building a B2B product where organizations and team management are core features.
Auth0 is the right choice only when you need enterprise SSO or compliance certifications. For everything else, it is more complex and more expensive than the alternatives.
Whichever you choose, choose early. Migrating auth providers mid-project is one of the most painful refactors in software development. Pick one, commit, and build.