better-auth

Files (10)

• SKILL.md
• advanced-features.md · references/
• database-integration.md · references/
• email-password-auth.md · references/
• oauth-providers.md · references/
• .coverage · scripts/
• better_auth_init.py · scripts/
• requirements.txt · scripts/
• .coverage · scripts/tests/
• test_better_auth_init.py · scripts/tests/

SKILL.md (first lines)

# 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

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

### Environment Setup

Create `.env`:
```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/):

```ts
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

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

### Mount API Handler

**Next.js App Router:**
```ts
// 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`:

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

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

### Basic Usage

```ts
// Sign up
await authClient.signUp.email({
  email: "user@example.com",
  password: "secure123",
  name: "John Doe"
});

// Sign in
await authClient.signIn.email({
  email: "user@example.com",
  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

| Feature | Plugin Required | Use Case | Reference |
|---------|----------------|----------|-----------|
| Email/Password | No (built-in) | Basic auth | [email-password-auth.md](./references/email-password-auth.md) |
| OAuth (GitHub, Google, etc.) | No (built-in) | Social login | [oauth-providers.md](./references/oauth-providers.md) |
| Email Verification | No (built-in) | Verify email addresses | [email-password-auth.md](./references/email-password-auth.md#email-verification) |
| Password Reset | No (built-in) | Forgot password flow | [email-password-auth.md](./references/email-password-auth.md#password-reset) |
| Two-Factor Auth (2FA/TOTP) | Yes (`twoFactor`) | Enhanced security | [advanced-features.md](./references/advanced-features.md#two-factor-authentication) |

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