better-auth

name

better-auth

description

Better Auth — framework-agnostic TypeScript authentication & authorization library. Covers setup, email/password, social OAuth (40+ providers), passkeys, magic links, 2FA, organizations, sessions, plugins, admin, hooks, and security hardening. Use when implementing auth with Better Auth: configuring auth instances, adding providers, setting up database adapters (Prisma, Drizzle, PostgreSQL, MySQL, SQLite, MongoDB), integrating with frameworks (Next.js, Nuxt, SvelteKit, Astro, Hono, Express, Elysia, Fastify, Expo), managing sessions, or extending with plugins.

Better Auth

Framework-agnostic TypeScript auth library. Plugin-based architecture, 40+ OAuth providers, 18+ framework integrations.

Quick Start

Install

npm install better-auth

Scoped packages (as needed):

Package	Use case
@better-auth/passkey	WebAuthn/Passkey auth
@better-auth/sso	SAML/OIDC enterprise SSO
@better-auth/stripe	Stripe payments
@better-auth/expo	React Native/Expo

Environment Variables

BETTER_AUTH_SECRET=<32+ chars, generate: openssl rand -base64 32>
BETTER_AUTH_URL=http://localhost:3000
DATABASE_URL=<connection string>

Server Config (lib/auth.ts)

import { betterAuth } from "better-auth";

export const auth = betterAuth({
  database: process.env.DATABASE_URL,  // or adapter instance
  emailAndPassword: { enabled: true },
  socialProviders: {
    google: {
      clientId: process.env.GOOGLE_CLIENT_ID!,
      clientSecret: process.env.GOOGLE_CLIENT_SECRET!,
    },
  },
  plugins: [], // add plugins here
});

export type Session = typeof auth.$Infer.Session;

Client Config (lib/auth-client.ts)

import { createAuthClient } from "better-auth/react"; // or /vue, /svelte, /solid, /client

export const authClient = createAuthClient({
  plugins: [], // add client plugins here
});

Route Handler

Framework	File	Handler
Next.js App Router	app/api/auth/[...all]/route.ts	toNextJsHandler(auth) → export { GET, POST }
Next.js Pages	pages/api/auth/[...all].ts	toNextJsHandler(auth) → default export
Express	any	app.all("/api/auth/*splat", toNodeHandler(auth))
Hono	route	app.on(["POST","GET"], "/api/auth/**", (c) => auth.handler(c.req.raw))
SvelteKit	hooks.server.ts	svelteKitHandler({ auth, event })
Astro	pages/api/auth/[...all].ts	toAstroHandler(auth)
Elysia	plugin	new Elysia().mount(auth.handler)

See references/framework-integrations.md for all frameworks.

CLI Commands

npx @better-auth/cli@latest migrate          # Apply schema (built-in adapter)
npx @better-auth/cli@latest generate          # Generate for Prisma/Drizzle
npx @better-auth/cli@latest generate --output prisma/schema.prisma
npx @better-auth/cli@latest generate --output src/db/auth-schema.ts

Re-run after adding/changing plugins.

Core Concepts

• Server instance (auth): handles all auth logic, DB, sessions
• Client instance (authClient): framework-specific hooks (useSession, signIn, signUp, signOut)
• Plugins: extend both server and client — add endpoints, DB tables, hooks
• Type inference: auth.$Infer.Session, auth.$Infer.Session.user for full type safety
• For separate client/server projects: createAuthClient<typeof auth>()

Authentication Methods

Method	Package	Config/Plugin	Reference
Email/Password	built-in	emailAndPassword: { enabled: true }	authentication.md
Social OAuth	built-in	socialProviders: { google: {...} }	authentication.md
Magic Link	built-in	magicLink() plugin	authentication.md
Passkey	@better-auth/passkey	passkey() plugin	authentication.md
Username	built-in	username() plugin	authentication.md
Email OTP	built-in	emailOtp() plugin	authentication.md
Phone Number	built-in	phoneNumber() plugin	authentication.md
Anonymous	built-in	anonymous() plugin	authentication.md

Plugin Quick Reference

Import from dedicated paths for tree-shaking: import { twoFactor } from "better-auth/plugins/two-factor" NOT from "better-auth/plugins".

Plugin	Server Import	Client Import	Purpose
twoFactor	better-auth/plugins/two-factor	twoFactorClient	TOTP, OTP, backup codes
organization	better-auth/plugins/organization	organizationClient	Multi-tenant orgs, teams, RBAC
admin	better-auth/plugins/admin	adminClient	User management, impersonation
passkey	@better-auth/passkey	passkeyClient	WebAuthn/FIDO2
magicLink	better-auth/plugins/magic-link	magicLinkClient	Passwordless email links
emailOtp	better-auth/plugins/email-otp	emailOtpClient	Email one-time passwords
username	better-auth/plugins/username	usernameClient	Username-based auth
phoneNumber	better-auth/plugins/phone-number	phoneNumberClient	Phone-based auth
anonymous	better-auth/plugins/anonymous	anonymousClient	Guest sessions
apiKey	better-auth/plugins/api-key	apiKeyClient	API key management
bearer	better-auth/plugins/bearer	—	Bearer token auth
jwt	better-auth/plugins/jwt	jwtClient	JWT tokens
multiSession	better-auth/plugins/multi-session	multiSessionClient	Multiple active sessions
oauthProvider	better-auth/plugins/oauth-provider	—	Become OAuth provider
oidcProvider	better-auth/plugins/oidc-provider	—	Become OIDC provider
sso	@better-auth/sso	ssoClient	SAML/OIDC enterprise SSO
openAPI	better-auth/plugins/open-api	—	API documentation
customSession	better-auth/plugins/custom-session	—	Extend session data
genericOAuth	better-auth/plugins/generic-oauth	genericOAuthClient	Custom OAuth providers
oneTap	better-auth/plugins/one-tap	oneTapClient	Google One Tap

Pattern: server plugin in auth({ plugins: [...] }) + client plugin in createAuthClient({ plugins: [...] }) + re-run CLI migrations.

See references/plugins.md for detailed usage and custom plugin creation.

Database Setup

Adapter	Setup
SQLite	Pass better-sqlite3 or bun:sqlite instance
PostgreSQL	Pass pg.Pool instance
MySQL	Pass mysql2 pool
Prisma	prismaAdapter(prisma, { provider: "postgresql" }) from better-auth/adapters/prisma
Drizzle	drizzleAdapter(db, { provider: "pg" }) from better-auth/adapters/drizzle
MongoDB	mongodbAdapter(db) from better-auth/adapters/mongodb
Connection string	database: process.env.DATABASE_URL (uses built-in Kysely)

Critical: Config uses ORM model name, NOT DB table name. Prisma model User mapping to table users → use modelName: "user".

Core schema tables: user, session, account, verification. Plugins add their own tables.

See references/setup.md for full database setup details.

Session Management

Key options:

session: {
  expiresIn: 60 * 60 * 24 * 7,  // 7 days (default)
  updateAge: 60 * 60 * 24,       // refresh every 24h (default)
  freshAge: 60 * 60 * 24,        // require re-auth after 24h for sensitive ops
  cookieCache: {
    enabled: true,
    maxAge: 300,                  // 5 min
    strategy: "compact",          // "compact" | "jwt" | "jwe"
  },
}

• secondaryStorage (Redis/KV): sessions go there by default, not DB
• Stateless mode: no DB + cookieCache = session in cookie only
• customSession plugin: extend session with custom fields

See references/sessions.md for full session management details.

Security Checklist

DO	DON'T
Use 32+ char secret with high entropy	Commit secrets to version control
Set baseURL with HTTPS in production	Disable CSRF check (disableCSRFCheck)
Configure trustedOrigins for all frontends	Disable origin check
Enable rate limiting (on by default in prod)	Use "memory" rate limit storage in serverless
Configure backgroundTasks.handler on serverless	Skip email verification setup
Use "jwe" cookie cache for sensitive session data	Store OAuth tokens unencrypted if used for API calls
Set revokeSessionsOnPasswordReset: true	Return specific error messages ("user not found")

See references/security.md for complete security hardening guide.

Common Gotchas

1. Model vs table name — config uses ORM model name, not DB table name
2. Plugin schema — re-run CLI after adding/changing plugins
3. Secondary storage — sessions go there by default, not DB. Set session.storeSessionInDatabase: true to persist both
4. Cookie cache — custom session fields NOT cached, always re-fetched from DB
5. Callback URLs — always use absolute URLs with origin (not relative paths)
6. Express v5 — use "/api/auth/*splat" not "/api/auth/*" for catch-all routes
7. Next.js RSC — add nextCookies() plugin to auth config for server component session access

Troubleshooting

Issue	Fix
"Secret not set"	Add BETTER_AUTH_SECRET env var
"Invalid Origin"	Add domain to trustedOrigins
Cookies not setting	Check baseURL matches domain; enable secure cookies in prod
OAuth callback errors	Verify redirect URIs in provider dashboard match exactly
Type errors after adding plugin	Re-run CLI generate/migrate
Session null in RSC	Add nextCookies() plugin
2FA redirect not working	Add twoFactorClient with onTwoFactorRedirect to client

Reference Index

File	When to read
setup.md	Setting up new project, configuring DB, route handlers
authentication.md	Implementing any auth method (email, social, passkey, magic link, etc.)
sessions.md	Configuring session expiry, caching, stateless mode, secondary storage
security.md	Hardening for production — rate limiting, CSRF, cookies, OAuth security
plugins.md	Using or creating plugins, plugin catalog
framework-integrations.md	Framework-specific setup (Next.js, Nuxt, SvelteKit, Hono, Express, etc.)
two-factor.md	Implementing 2FA (TOTP, OTP, backup codes, trusted devices)
organizations.md	Multi-tenant orgs, teams, invitations, RBAC
admin.md	User management, roles, banning, impersonation
hooks-and-middleware.md	Custom logic via before/after hooks, DB hooks, middleware