Auth.js (NextAuth)
Open-source library for Next.js, SvelteKit, SolidStart. Free, self-managed user database.
VISIT AUTH.JS (NEXTAUTH)Quick facts
- CategoryLibrary / OSS
- LanguageTypeScript
- PricingOpen source
- LicenseISC
- Created2016
- GitHub stars26.4k
- HIPAA-eligibleNo
- SSO / SAMLLimited / paid
What it is
Auth.js (formerly NextAuth.js) is the standard open-source auth library for Next.js, SvelteKit, and SolidStart. Provider-based — wire up Google, GitHub, email, credentials, etc. You own the user database; library handles the OAuth dances and session management.
Best for
- Next.js / SvelteKit / SolidStart teams that want zero auth bill
- Apps where owning the user database is the priority
- Projects with simple auth needs (social login + email)
When not to pick it
Skip Auth.js for complex multi-tenant briefs — the abstractions get awkward at organisation-with-members shape. Skip for teams that want pre-built UI; you build the components yourself.
My take
Auth.js is the default zero-cost auth library for the React ecosystem. Trade-off is that you build the UI and the user-management surfaces yourself.
Links
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If Auth.js (NextAuth) is your pick — the next conversation is short
The 30-min call is where your auth choice becomes a real architecture, a migration plan if you are switching, and a price range you can take to your stakeholders. Describe your stack, your scale, your compliance constraints. I tell you whether Auth.js (NextAuth) is genuinely your fit.