better-auth

Better Auth Skill

Better Auth is comprehensive, framework-agnostic authentication/authorization framework for TypeScript with built-in email/password, social OAuth, and powerful plugin ecosystem for advanced features.

When to Use

• Implementing auth in TypeScript/JavaScript applications
• Adding email/password or social OAuth authentication
• Setting up 2FA, passkeys, magic links, advanced auth features
• Building multi-tenant apps with organization support
• Managing sessions and user lifecycle
• Working with any framework (Next.js, Nuxt, SvelteKit, Remix, Astro, Hono, Express, etc.)

Quick Start

Installation

npm install better-auth
# or pnpm/yarn/bun add better-auth

Environment Setup

Create .env:

BETTER_AUTH_SECRET=<generated-secret-32-chars-min>
BETTER_AUTH_URL=http://localhost:3000

Basic Server Setup

Create auth.ts (root, lib/, utils/, or under src/app/server/):

import { betterAuth } from "better-auth";

export const auth = betterAuth({
  database: {
    // See references/database-integration.md
  },
  emailAndPassword: {
    enabled: true,
    autoSignIn: true
  },
  socialProviders: {
    github: {
      clientId: process.env.GITHUB_CLIENT_ID!,
      clientSecret: process.env.GITHUB_CLIENT_SECRET!,
    }
  }
});

Database Schema

npx @better-auth/cli generate  # Generate schema/migrations
npx @better-auth/cli migrate   # Apply migrations (Kysely only)

Mount API Handler

Next.js App Router:

// app/api/auth/[...all]/route.ts
import { auth } from "@/lib/auth";
import { toNextJsHandler } from "better-auth/next-js";

export const { POST, GET } = toNextJsHandler(auth);

Other frameworks: See references/email-password-auth.md#framework-setup

Client Setup

Create auth-client.ts:

import { createAuthClient } from "better-auth/client";

export const authClient = createAuthClient({
  baseURL: process.env.NEXT_PUBLIC_BETTER_AUTH_URL || "http://localhost:3000"
});