Better Auth

Overview

Better Auth is an authentication library for Next.js. It provides a complete auth system with email/password, session management, React hooks, and an Organization plugin for multi-tenant access control.

Quick Start

npm add better-auth
npx auth@latest secret

Set BETTER_AUTH_SECRET, BETTER_AUTH_URL, NEXT_PUBLIC_APP_URL in .env.

Architecture

Next.js App
├── API Route: /api/auth/[...all]  ← toNextJsHandler(auth)
│   ├── POST /api/auth/sign-in     ← Login
│   ├── POST /api/auth/sign-up     ← Register
│   ├── POST /api/auth/sign-out    ← Logout
│   └── GET  /api/auth/get-session ← Current session
│
├── Auth Config: src/lib/auth.ts   ← betterAuth({ ... })
│
├── Auth Client: src/lib/auth-client.ts  ← createAuthClient()
│   └── organizationClient()       ← org plugin (optional)
│
└── Auth Provider (optional)       ← React Context wrapper
    └── useAuth() hook

Quick Reference

import { auth } from "@/lib/auth"
import { authClient } from "@/lib/auth-client"
const { signIn, signUp, signOut, useSession } = authClient

// Sign in
const result = await signIn.email({ email, password })
if (result.error) { /* handle */ }

// Session
const { data: session, isPending } = useSession()

Organization Plugin

See references/organization-plugin.md for full setup.

// Client hooks
const { data: orgs } = authClient.useListOrganizations()
const { data: activeOrg } = authClient.useActiveOrganization()

// Mutations
await authClient.organization.setActive({ organizationId: orgId })
await authClient.organization.inviteMember({ email, role: "member", organizationId: orgId })

Key Files