Better Auth Integration Guide

Reference Repositories

• Better Auth — TypeScript authentication framework with plugins

Upstream Grounding

When Better Auth API signatures, adapter behavior, generated schema, plugin options, session storage, cookie behavior, or security defaults affect correctness, ask DeepWiki a narrow question against better-auth/better-auth before relying on memory. Use it to orient, then verify decisive details against local installed types, source, or official docs before changing code.

Skip DeepWiki for stable setup basics already documented below.

Always consult better-auth.com/docs for code examples and latest API.

Setup Workflow

1. Install: bun add better-auth
2. Set env vars: BETTERAUTHSECRET and BETTERAUTHURL
3. Create auth.ts with database + config
4. Create route handler for your framework
5. Run bun x @better-auth/cli@latest migrate
6. Verify: call GET /api/auth/ok — should return { status: "ok" }

Quick Reference

Environment Variables

• BETTERAUTHSECRET - Encryption secret (min 32 chars). Generate: openssl rand -base64 32
• BETTERAUTHURL - Base URL (e.g., https://example.com)

Only define baseURL/secret in config if env vars are NOT set.

File Location

CLI looks for auth.ts in: ./, ./lib, ./utils, or under ./src. Use --config for custom path.

CLI Commands

• bun x @better-auth/cli@latest migrate - Apply schema (built-in adapter)
• bun x @better-auth/cli@latest generate - Generate schema for Prisma/Drizzle
• bun x @better-auth/cli@latest mcp --cursor - Add MCP to AI tools

Re-run after adding/changing plugins.

Core Config Options

Database

Direct connections: Pass pg.Pool, mysql2 pool, better-sqlite3, or bun:sqlite instance.

ORM adapters: Import from better-auth/adapters/drizzle, better-auth/adapters/prisma, better-auth/adapters/mongodb.

Critical: Better Auth uses adapter model names, NOT underlying table names. If Prisma model is User mapping to table users, use modelName: "user" (Prisma reference), not "users".

Session Management

Storage priority:

1. If secondaryStorage defined → sessions go there (not DB)
2. Set session.storeSessionInDatabase: true to also persist to DB
3. No database + cookieCache → fully stateless mode

Cookie cache strategies:

• compact (default) - Base64url + HMAC. Smallest.
• jwt - Standard JWT. Readable but signed.
• jwe - Encrypted. Maximum security.

Key options: session.expiresIn (default 7 days), session.updateAge (refresh interval), session.cookieCache.maxAge, session.cookieCache.version (change to invalidate all sessions).

User & Account Config

User: user.modelName, user.fields (column mapping), user.additionalFields, user.changeEmail.enabled (disabled by default), user.deleteUser.enabled (disabled by default).

Account: account.modelName, account.accountLinking.enabled, account.storeAccountCookie (for stateless OAuth).

Required for registration: email and name fields.

Email Flows

• emailVerification.sendVerificationEmail - Must be defined for verification to work
• emailVerification.sendOnSignUp / sendOnSignIn - Auto-send triggers
• emailAndPassword.sendResetPassword - Password reset email handler

Security

In advanced:

• useSecureCookies - Force HTTPS cookies
• disableCSRFCheck - ⚠️ Security risk
• disableOriginCheck - ⚠️ Security risk
• crossSubDomainCookies.enabled - Share cookies across subdomains
• ipAddress.ipAddressHeaders - Custom IP headers for proxies
• database.generateId - Custom ID generation or "serial"/"uuid"/false

Rate limiting: rateLimit.enabled, rateLimit.window, rateLimit.max, rateLimit.storage ("memory" | "database" | "secondary-storage").

Hono, Cookies, And OAuth Provider Boundaries

• Mount Better Auth handlers for both GET and POST auth paths.
• Register credentialed CORS before Better Auth when browser callers use cookies. Coordinate credentials: true, trustedOrigins, secure cookies, and origin checks.
• Treat baseURL as security-sensitive: it drives redirects, issuer URLs, cookie behavior, and OAuth validation. Dynamic base URLs need explicit host or origin validation.
• Treat trustedOrigins as a CSRF and redirect boundary, not a convenience list.
• Do not disable CSRF or origin checks in production. disableOriginCheck also weakens CSRF protection.
• Make secure cookie behavior explicit in production, even if Better Auth can infer it from HTTPS.
• If secondaryStorage is configured, sessions may not persist to the database unless session.storeSessionInDatabase is set. Put OAuth verification records in durable storage when KV consistency or cross-isolate reads matter.
• For OAuth provider work, document PKCE, trusted clients, JWT or JWKS signing choices, audience and issuer validation, discovery endpoints, and resource-server token verification.

Hooks

Endpoint hooks: hooks.before / hooks.after - Array of { matcher, handler }. Use createAuthMiddleware. Access ctx.path, ctx.context.returned (after), ctx.context.session.

Database hooks: databaseHooks.user.create.before/after, same for session, account. Useful for adding default values or post-creation actions.

Hook context (ctx.context): session, secret, authCookies, password.hash()/verify(), adapter, internalAdapter, generateId(), tables, baseURL.

Plugins

Import from dedicated paths for tree-shaking:

import { twoFactor } from "better-auth/plugins/two-factor"

NOT from "better-auth/plugins".

Popular plugins: twoFactor, organization, passkey, magicLink, emailOtp, username, phoneNumber, admin, apiKey, bearer, jwt, multiSession, sso, oauthProvider, oidcProvider, openAPI, genericOAuth.

Client plugins go in createAuthClient({ plugins: [...] }).

Client

Import from: better-auth/client (vanilla), better-auth/react, better-auth/vue, better-auth/svelte, better-auth/solid.

Key methods: signUp.email(), signIn.email(), signIn.social(), signOut(), useSession(), getSession(), revokeSession(), revokeSessions().

Type Safety

Infer types: typeof auth.$Infer.Session, typeof auth.$Infer.Session.user.

For separate client/server projects: createAuthClient<typeof auth>().

Common Gotchas

1. Model vs table name - Config uses ORM model name, not DB table name
2. Plugin schema - Re-run CLI after adding plugins
3. Secondary storage - Sessions go there by default, not DB
4. Cookie cache - Custom session fields NOT cached, always re-fetched
5. Stateless mode - No DB = session in cookie only, logout on cache expiry
6. Change email flow - Sends to current email first, then new email

Resources

• Docs
• Options Reference
• LLMs.txt
• GitHub
• Init Options Source