Stop guessing which one. Put them side by side.

The grid says what these tools are. This says what builders did about it — one decision per person, changeable whenever you change your mind.

# Tool comparison — Clerk vs Better Auth vs Lucia

Source: Kbaise, a directory of tools that work with Lovable projects.
Pick one and tell me why before writing any integration code.

## Clerk (clerk)
- URL: https://clerk.com
- Category: Auth & user management
- Cost: mixed — Free to 50k MRU · $25/mo Pro then $0.02/MRU
- What it is: Hosted authentication with prebuilt React and Next.js components — sign-in, user profile and organization UI you drop in as JSX. Handles sessions, MFA, passkeys, social login and B2B organizations. Billing is measured in monthly retained users rather than raw signups, so users who never return are never charged.
- Why builders pick it: Fastest zero-to-login path in the React world: drop in the SignIn component and you have a styled production auth page in minutes. The Feb 2026 jump to 50k free users made it viable far longer than before.
- Trap: The free tier jumped to 50k MRU in February 2026, but enterprise SSO, user impersonation and enhanced B2B org features sit behind $100/mo add-ons that stack on top of Pro. Clerk-hosted components mean your login UI lives in their iframe-free but proprietary React layer.
- Wiring: npm i @clerk/nextjs
- Full dossier: /api/public/tools/clerk

## Better Auth (better-auth)
- URL: https://better-auth.com
- Category: Auth & user management
- Cost: free — Free and open source (MIT) · self-hosted, no MAU fees
- What it is: Framework-agnostic TypeScript authentication library that runs inside your own app and writes to your own database. Covers email/password, social OAuth, two-factor, organizations, passkeys and API keys through a plugin system. Vercel acquired the project in July 2026; it stays MIT-licensed, self-hosted and community-governed.
- Why builders pick it: No per-MAU bill ever and no vendor holding your user table — auth becomes just another dependency. The plugin system covers most of what you would otherwise pay Clerk or Auth0 for.
- Trap: You own the hard parts: session security, email deliverability, rate limiting and breach response are all yours. Vercel's July 2026 acquisition preserves MIT licensing, but roadmap direction now sits with a hosting vendor.
- Wiring: npm i better-auth
- Full dossier: /api/public/tools/better-auth

## Lucia (lucia)
- URL: https://lucia-auth.com
- Category: Auth & user management
- Cost: free — Free · deprecated library, now MIT reference code and a written guide
- What it is: No longer a library. Lucia was deprecated in March 2025 and now exists as a learning resource: a copy-paste auth_session.ts reference implementation plus The Auth Book, a free guide covering sessions, tokens and password handling. The site was last refreshed in July 2026.
- Why builders pick it: Read it before choosing any vendor — it is the fastest way to genuinely understand what session auth does, and the single-file implementation is enough for small projects.
- Trap: Do not install the npm package for new work; it is unmaintained and will not receive security fixes. This is documentation and example code, not a supported dependency.
- Full dossier: /api/public/tools/lucia

## Quick read

- Free with no card: Better Auth, Lucia.

## Rules
1. Prefer the free tier when no budget was stated, and say what the ceiling is.
2. Read the full dossier before integrating.
3. Fetch /api/public/models before writing any AI model ID.

Agents can fetch the same thing: GET /api/public/compare?slugs=clerk,better-auth,lucia