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"
});

Basic Usage

// Sign up
await authClient.signUp.email({
  email: "[email protected]",
  password: "secure123",
  name: "John Doe"
});

// Sign in
await authClient.signIn.email({
  email: "[email protected]",
  password: "secure123"
});

// OAuth
await authClient.signIn.social({ provider: "github" });

// Session
const { data: session } = authClient.useSession(); // React/​Vue/​Svelte
const { data: session } = await authClient.getSession(); // Vanilla JS

Feature Selection Matrix

Auth Method Selection Guide

Choose Email/​Password when:

• Building standard web app with traditional auth
• Need full control over user credentials
• Targeting users who prefer email-based accounts

Choose OAuth when:

• Want quick signup with minimal friction
• Users already have social accounts
• Need access to social profile data

Choose Passkeys when:

• Want passwordless experience
• Targeting modern browsers/​devices
• Security is top priority

Choose Magic Link when:

• Want passwordless without WebAuthn complexity
• Targeting email-first users
• Need temporary access links

Combine Multiple Methods when:

• Want flexibility for different user preferences
• Building enterprise apps with various auth requirements
• Need progressive enhancement (start simple, add more options)

Core Architecture

Better Auth uses client-server architecture:

1. Server (better-auth): Handles auth logic, database ops, API routes
2. Client (better-auth/​client): Provides hooks/​methods for frontend
3. Plugins: Extend both server/​client functionality

Implementation Checklist

• Install better-auth package
• Set environment variables (SECRET, URL)
• Create auth server instance with database config
• Run schema migration (npx @better-auth/​cli generate)
• Mount API handler in framework
• Create client instance
• Implement sign-up/​sign-in UI
• Add session management to components
• Set up protected routes/​middleware
• Add plugins as needed (regenerate schema after)
• Test complete auth flow
• Configure email sending (verification/​reset)
• Enable rate limiting for production
• Set up error handling

Reference Documentation

Core Authentication

• Email/​Password Authentication - Email/​password setup, verification, password reset, username auth
• OAuth Providers - Social login setup, provider configuration, token management
• Database Integration - Database adapters, schema setup, migrations

Advanced Features

• Advanced Features - 2FA/​MFA, passkeys, magic links, organizations, rate limiting, session management

Scripts

• scripts/​better_auth_init.py - Initialize Better Auth configuration with interactive setup

Resources

• Docs: https://www.better-auth.com/docs
• GitHub: https://github.com/better-auth/better-auth
• Plugins: https://www.better-auth.com/docs/plugins
• Examples: https://www.better-auth.com/docs/examples