better-auth
Package: better-auth@1.4.15 (ESM-only since v1.4.0) Docs: https://better-auth.com/docs | GitHub: https://github.com/better-auth/better-auth
Environment Setup
| Variable | Purpose |
|---|---|
BETTER_AUTH_SECRET | Encryption secret (min 32 chars). Generate: openssl rand -base64 32 |
BETTER_AUTH_URL | Base URL (e.g., https://example.com) |
Only define baseURL/secret in config if env vars are NOT set. CLI looks for auth.ts in: ./, ./lib, ./utils, or ./src.
Core Config Options
| Option | Notes |
|---|---|
appName | Optional display name |
baseURL | Only if BETTER_AUTH_URL not set |
basePath | Default /api/auth. Set / for root. |
secret | Only if BETTER_AUTH_SECRET not set |
database | Required unless using stateless mode (v1.4+) |
secondaryStorage | Redis/KV for sessions and rate limits |
emailAndPassword | { enabled: true } to activate |
socialProviders | { google: { clientId, clientSecret }, ... } |
plugins | Array of plugins |
trustedOrigins | CSRF whitelist |
Plugin Reference
| Plugin | Description |
|---|---|
| twoFactor | TOTP, email OTP, backup codes |
| organization | Multi-tenant orgs, teams, invitations, RBAC |
| admin | User management, impersonation, banning |
| passkey | WebAuthn passwordless login |
| magicLink | Email-based passwordless login |
| jwt | JWT tokens with key rotation, JWKS |
| oauthProvider | Build your own OAuth 2.1 provider (separate @better-auth/oauth-provider package) |
| sso | Enterprise SSO with OIDC, OAuth2, SAML 2.0 (separate @better-auth/sso package) |
| scim | Enterprise user provisioning (separate @better-auth/scim package) |
| stripe | Payment and subscription management |
| bearer | API token auth for mobile/CLI |
| apiKey | Token-based auth with rate limits |
| oneTap | Google One Tap frictionless sign-in |
| anonymous | Guest user access without PII |
| genericOAuth | Custom OAuth providers with PKCE |
| emailOTP | Email-based one-time password auth |
| phoneNumber | Phone/SMS-based OTP sign-in |
| username | Username-based sign-in (alternative to email) |
| multiSession | Multiple accounts in same browser |
| openAPI | Interactive API docs at /api/auth/reference |
Session Strategies
| Strategy | Format | Use Case |
|---|---|---|
| Compact (default) | Base64url + HMAC-SHA256 | Smallest, fastest |
| JWT | Standard JWT | Interoperable |
| JWE | A256CBC-HS512 encrypted | Most secure |
Getting Started
For new projects or first-time Better Auth setup, use the official interactive setup skill:
npx skills add better-auth/skills -s create-auth-skill
This walks through framework detection, database selection, auth method choices, plugin setup, and generates the initial configuration.
Anti-Patterns
| Anti-Pattern | Correct Approach |
|---|---|
Using d1Adapter | Use Drizzle or Kysely adapter with provider: "sqlite" |
| Using table name in config | Use ORM model name, not DB table name |
| Forgetting CLI after plugin changes | Re-run npx @better-auth/cli@latest generate |
tanstackStartCookies() not last plugin | Must be the last plugin in array (TanStack Start) |
Checking session for login state | Check session?.user — session object is always truthy |
Missing nodejs_compat flag | Required in wrangler.toml for Cloudflare Workers |
| Kysely CamelCasePlugin with auth | Use separate Kysely instance without the plugin |
Using old reactStartCookies import | Renamed to tanstackStartCookies from better-auth/tanstack-start in v1.4.14 |
Common Mistakes
| Mistake | Correct Pattern |
|---|---|
Setting baseURL and secret in config when env vars are already set | Only define these in config if BETTER_AUTH_URL and BETTER_AUTH_SECRET env vars are NOT set |
| Using CommonJS require syntax with better-auth v1.4+ | better-auth is ESM-only since v1.4.0; use import syntax exclusively |
| Not re-running CLI generate after adding or changing plugins | Always run npx @better-auth/cli@latest generate after plugin changes to update DB schema |
Checking session object truthy state for login detection | Check session?.user instead; the session object itself is always truthy |
Using d1Adapter directly for Cloudflare D1 | Use Drizzle or Kysely adapter with provider: "sqlite" for D1 compatibility |
Breaking Changes
| Version | Change |
|---|---|
| v1.4.14 | reactStartCookies renamed to tanstackStartCookies (import from better-auth/tanstack-start) |
| v1.4.6 | allowImpersonatingAdmins defaults to false |
| v1.4.0 | ESM-only (no CommonJS); SSO, SCIM, OAuth Provider moved to separate packages |
| v1.3.0 | Multi-team table structure: new teamMembers table needed |
Delegation
When working on auth, delegate to:
application-security— Security architecture and threat modelingdatabase— Drizzle ORM schema and migrationstanstack-start— TanStack Start integration patterns
Resources
- Docs: https://better-auth.com/docs
- Options Reference: https://better-auth.com/docs/reference/options
- LLMs.txt: https://better-auth.com/llms.txt
- Changelog: https://www.better-auth.com/changelogs
- TanStack Start: https://www.better-auth.com/docs/integrations/tanstack
- Expo: https://www.better-auth.com/docs/integrations/expo
References
- Database Adapters — Drizzle, Kysely, Prisma adapters, Cloudflare Workers factory pattern
- Session Management — Cookie cache, stateless sessions, storage priority, freshAge constraints
- Plugins and Social Auth — Plugin setup, OAuth 2.1 provider, admin RBAC, social provider scopes
- Email and Password — Verification, password reset, timing attack prevention, hashing (scrypt, argon2), token security
- Two-Factor Authentication — TOTP, email/SMS OTP, backup codes, trusted devices, 2FA session flow
- Organizations — Multi-tenant orgs, teams, invitations, RBAC, dynamic access control, lifecycle hooks
- Configuration — User/account config, rate limiting, hooks, CSRF, trusted origins, cookie/OAuth security, production checklist
- Framework Integration — TanStack Start setup, Expo/React Native, client imports, type safety
- Migration Guides — Migrate from NextAuth/Auth.js, Clerk, or Supabase Auth with schema mappings and session strategies
- Troubleshooting — D1 consistency, CORS, OAuth redirect, admin 403, nanostore refresh, known bugs