Auth.js vs Better Auth for SvelteKit
Auth.js and Better Auth both answer the same question in a SvelteKit project: how do users sign in? The long-running open source auth layer formerly called NextAuth, mostly a thin wrapper around OAuth providers. Open source TypeScript auth library that keeps sessions and users in your own database, extended through plugins. Better Auth covers more of the ecosystem, so it survives a change of framework; Auth.js is the better fit while you stay where it is strongest.
Verdict
Better Auth covers more of the ecosystem, so it survives a change of framework; Auth.js is the better fit while you stay where it is strongest. For SvelteKit specifically, both are supported, so let the tradeoff above decide rather than the framework.
Pick Auth.js if
- ✓Enormous library of OAuth providers configured with a few lines each.
- ✓Years of production usage mean most errors already have a forum answer.
- ✓Adapters let you keep sessions in whichever database you already chose.
Pick Better Auth if
- ✓User and session tables sit in your database, so joins are ordinary SQL.
- ✓Plugin system covers passkeys, two factor and organizations without vendor lock-in.
- ✓Fully typed API surface, so misuse usually shows up at compile time.
| Comparison | Auth.js | Better Auth |
|---|---|---|
| Pricing shape | Free and open source. Costs are whatever your identity providers and database charge. | Free and open source. You pay only for the database and server it runs on. |
| Frameworks | Next.js, SvelteKit | Next.js, SvelteKit, Nuxt, Expo |
| In one line | The long-running open source auth layer formerly called NextAuth, mostly a thin wrapper around OAuth providers. | Open source TypeScript auth library that keeps sessions and users in your own database, extended through plugins. |
Pricing described qualitatively because published plans change often. Checked 2026-08-23. Confirm current terms on Auth.js and Better Auth.
Auth.js
Strengths
- ✓Enormous library of OAuth providers configured with a few lines each.
- ✓Years of production usage mean most errors already have a forum answer.
- ✓Adapters let you keep sessions in whichever database you already chose.
- ✓Stateless JWT sessions work without any session store at all.
Tradeoffs
- ✗Anything past OAuth, like invitations or roles, you design yourself.
- ✗Callback and adapter APIs have churned across major versions more than once.
- ✗Documentation lags the code, so reading the source becomes routine.
- ✗Debugging silent callback failures is a known rite of passage.
Better Auth
Strengths
- ✓User and session tables sit in your database, so joins are ordinary SQL.
- ✓Plugin system covers passkeys, two factor and organizations without vendor lock-in.
- ✓Fully typed API surface, so misuse usually shows up at compile time.
- ✓No per-user cost, which makes free tiers and large user bases cheap.
Tradeoffs
- ✗You run and patch the auth code yourself, including security updates.
- ✗Login screens are your responsibility, since the library ships logic not UI.
- ✗Younger project, so APIs still move and older guides go stale quickly.
- ✗Compliance evidence like SOC 2 covers your infrastructure, not a vendor's.
Same pair, different context
Frequently asked questions
Is Auth.js or Better Auth better in a SvelteKit project?
Neither is better in the abstract. Better Auth covers more of the ecosystem, so it survives a change of framework; Auth.js is the better fit while you stay where it is strongest. Pick the one whose downside you can absorb, because both upsides are real.
What is the main drawback of Auth.js?
Anything past OAuth, like invitations or roles, you design yourself. Callback and adapter APIs have churned across major versions more than once.
What is the main drawback of Better Auth?
You run and patch the auth code yourself, including security updates. Login screens are your responsibility, since the library ships logic not UI.
Do Auth.js and Better Auth both support SvelteKit?
Yes, both list support for SvelteKit, which is why this comparison exists as a SvelteKit page. SvelteKit moved fast enough that training data contains three incompatible generations of it: Sapper, SvelteKit 1.0, and SvelteKit 2 on Svelte 5.