Clerk vs AuthJS for Solo Developers

Quick Comparison

Clerk Overview

Clerk is a fully managed auth service with pre-built React components. You install the package, add <SignIn /> to your page, configure your providers in the dashboard, and authentication works. Social logins, email/password, multi-factor auth, user profiles, and organization management are all included and ready to use.

The components are well-designed and customizable. They handle edge cases like password strength validation, email verification flows, MFA setup, and account recovery without you writing any of that logic. The middleware integration for Next.js makes route protection a one-liner.

Clerk stores user data on their servers and provides APIs and hooks to access it. The management dashboard gives you user insights, session details, and administrative controls. For a solo developer, it means auth is completely off your plate.

AuthJS Overview

AuthJS, formerly NextAuth.js, is an open-source authentication library for JavaScript applications. It started as a Next.js-specific solution and has expanded to support SvelteKit, Express, SolidStart, and other frameworks. You configure providers, session handling, and callbacks, then AuthJS manages the OAuth flows and session cookies.

AuthJS supports 80+ OAuth providers out of the box: Google, GitHub, Discord, Twitter, and many more. Database adapters connect to Prisma, Drizzle, Supabase, MongoDB, and other ORMs/databases. Sessions can be stored in JWTs (stateless) or in a database (stateful).

The library is free, open source, and runs entirely on your infrastructure. User data lives in your database. Session management runs on your server. There's no external service dependency and no per-user costs regardless of scale.

The trade-off: AuthJS provides no UI. You build your own sign-in forms, user settings pages, and account management flows. It handles the auth logic, you handle everything the user sees.

Key Differences

UI components. Clerk gives you production-ready sign-in, sign-up, user profile, and organization components. AuthJS gives you nothing visual. You design and implement every screen. For rapid prototyping, Clerk saves days of work. For design-heavy projects where you need complete control over every pixel, AuthJS's blank slate might actually be preferred.

Cost at scale. AuthJS is free at any scale. 10 users or 10 million users, same cost: $0 for the library (you pay for your own infrastructure). Clerk is free up to 10,000 MAU, then $25/month plus per-user fees. For a consumer app that grows beyond 10K users, the cost difference is real.

Setup time. Clerk: install package, add provider, wrap your app, drop in components. Total: 15-20 minutes. AuthJS: install package, configure providers, set up database adapter, create API routes, build sign-in pages, implement session checks on protected routes. Total: 2-4 hours for a basic setup, longer for polished flows.

Data ownership. AuthJS stores all data in your database. You control it entirely. Clerk stores user data on their servers. You access it through their API. If data sovereignty matters for your use case, AuthJS keeps everything under your roof.

Session management. Clerk handles session management, token rotation, multi-device sessions, and revocation through their service. AuthJS gives you JWT-based or database-based sessions that you configure. Both work, but Clerk's implementation requires zero thought while AuthJS requires understanding session strategies and their trade-offs.

Framework support. AuthJS works with Next.js, SvelteKit, Express, SolidStart, and others. Clerk is heavily optimized for React and Next.js, with basic support for other frameworks. If you're building with SvelteKit, AuthJS has better native support.

Community and stability. AuthJS has a massive community. It's one of the most popular auth libraries in the JavaScript ecosystem with years of production use. Clerk is newer but well-funded and growing fast. Both are actively maintained.

When to Choose Clerk

• You want auth working in 15 minutes with production-ready UI
• You're building with React or Next.js where Clerk's integration is strongest
• You don't want to build login forms, profile pages, or account management
• You want a managed service handling security updates and token management
• Your project is pre-revenue and the 10,000 MAU free tier covers your needs

When to Choose AuthJS

• You want zero ongoing costs for authentication at any scale
• You need complete control over the auth UI and user experience
• You want all user data in your own database
• You're building with SvelteKit, SolidStart, or another non-React framework
• You have the time to invest in building auth flows properly

The Verdict

For solo developers building a Next.js product and racing to launch, Clerk is the faster path. The pre-built components, managed sessions, and user management dashboard eliminate hours of work on something that isn't your core product. Auth is a solved problem, and Clerk solves it quickly.

For solo developers building for the long term, or on a strict zero-budget, AuthJS is the sustainable choice. No per-user pricing means your auth cost is fixed at $0 regardless of growth. You invest more time upfront but avoid a recurring dependency on a paid service.

Here's the practical take: if your biggest constraint is time (you need to launch), use Clerk. If your biggest constraint is money (you need to stay free), use AuthJS. Both are excellent, well-maintained solutions. The auth library wars matter less than shipping your product, and both tools let you do that effectively.