Lucia vs Supabase Auth for Solo Developers

Quick Comparison

Lucia Overview

Lucia is an open-source authentication library that provides session management, cookie handling, and token generation without prescribing how your auth should work. You install it, connect a database adapter, and build your authentication flows using Lucia's functions. Everything else, the forms, the OAuth integration, the middleware, is your responsibility.

The design is deliberate. Lucia handles the security-critical parts (session tokens, secure cookies, CSRF protection) and lets you control the rest. Your database schema, your user model, your business logic. No vendor lock-in, no dashboard, no external API calls during authentication.

I built auth with Lucia in a project where sessions needed to carry custom data and expire based on business rules no managed service would support. Lucia let me define exactly what a session contained and when it expired. That flexibility was the whole point.

Supabase Auth Overview

Supabase Auth is the authentication system built into the Supabase platform. It supports email/password, magic links, phone auth, and social OAuth providers. The defining feature is its integration with PostgreSQL Row Level Security, where RLS policies reference auth.uid() to control data access at the database level.

The free tier offers 50,000 MAU. Users are stored in your PostgreSQL database in the auth schema. The JavaScript client handles session management automatically. Social providers are toggled in the dashboard and configured with OAuth credentials.

I use Supabase Auth in a project where the entire backend is Supabase. The auth-to-database pipeline is seamless: user logs in, RLS policies enforce access, queries return only the right data. I never wrote authorization middleware because the database handles it.

Key Differences

Setup time. Supabase Auth takes 15-20 minutes. Enable providers in the dashboard, initialize the client, call signInWithOAuth() or signUp(). Lucia takes a few hours because you're building the registration form, login handler, session middleware, and password hashing yourself. If speed to working auth matters, Supabase wins by a wide margin.

Database integration. Supabase Auth integrates with Row Level Security at the PostgreSQL level. RLS policies like auth.uid() = user_id enforce access control without application code. Lucia stores sessions in whatever database you configure, but your application code handles authorization. Supabase's approach eliminates a whole category of authorization bugs. Lucia's approach gives you more flexibility but more responsibility.

Data ownership. Both solutions store user data in your database. With Supabase, it's in the auth schema of your Supabase PostgreSQL instance (exportable). With Lucia, it's in whatever database you choose with whatever schema you design. Both give you real data ownership, but Lucia gives you complete schema control.

Cost. Both are free for most solo developers. Lucia has no usage limits. Supabase Auth is free up to 50,000 MAU (part of the Supabase free tier). At that scale, neither costs anything. Beyond 50,000 MAU, Supabase Auth is included with Supabase Pro ($25/month), while Lucia remains free.

Social login. Supabase Auth makes social login easy: toggle the provider, add OAuth credentials, call signInWithOAuth(). Lucia requires you to implement OAuth flows yourself, typically using a library like Arctic. The OAuth dance (redirect, callback, token exchange) is more code and more testing. Supabase abstracts this away.

Flexibility. Lucia gives you complete control over session behavior, token contents, and auth flows. You can implement auth patterns that Supabase Auth doesn't support: custom session metadata, non-standard expiry logic, hybrid auth schemes. Supabase Auth is flexible within its boundaries but has boundaries.

When to Choose Lucia

• You need custom session or token behavior that managed services can't support
• You want to use a database that isn't PostgreSQL (MongoDB, MySQL, etc.)
• Complete control over your auth schema and logic is a priority
• You're building something where auth needs to work differently than standard patterns
• Zero external dependencies for authentication is important

When to Choose Supabase Auth

• You're using Supabase as your backend (this is the obvious choice)
• Row Level Security integration for database-level access control appeals to you
• Speed of setup matters and you want auth working in 20 minutes
• You want social login without implementing OAuth flows manually
• The 50,000 MAU free tier aligns with your budget

The Verdict

For solo developers using Supabase, the choice is clear: use Supabase Auth. The RLS integration is genuinely powerful and eliminates authorization bugs by design. You'll have auth working quickly and it integrates perfectly with the rest of your stack. Choosing Lucia when you're on Supabase would mean giving up one of the platform's best features.

For solo developers NOT using Supabase who need custom auth behavior, Lucia is a solid library. It handles the hard security parts and lets you build exactly the auth system you need. But be honest about whether your requirements are actually custom or if you're over-engineering. Most apps need standard login, signup, and social auth, which Supabase Auth handles with much less code.

My recommendation: if Supabase is your backend, use Supabase Auth without thinking twice. If you're on a different backend and genuinely need custom auth logic, Lucia is excellent. If you just need standard auth on a different backend, there are managed solutions (Clerk, AuthJS) that will be faster than building with Lucia.