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skills/better-auth/references/email-password-auth.md

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+# Email/Password Authentication
+
+Email/password is built-in auth method in Better Auth. No plugins required for basic functionality.
+
+## Server Configuration
+
+### Basic Setup
+
+```ts
+import { betterAuth } from "better-auth";
+
+export const auth = betterAuth({
+  emailAndPassword: {
+    enabled: true,
+    autoSignIn: true, // Auto sign-in after signup (default: true)
+    requireEmailVerification: false, // Require email verification before login
+    sendResetPasswordToken: async ({ user, url }) => {
+      // Send password reset email
+      await sendEmail(user.email, url);
+    }
+  }
+});
+```
+
+### Custom Password Requirements
+
+```ts
+export const auth = betterAuth({
+  emailAndPassword: {
+    enabled: true,
+    password: {
+      minLength: 8,
+      requireUppercase: true,
+      requireLowercase: true,
+      requireNumbers: true,
+      requireSpecialChars: true
+    }
+  }
+});
+```
+
+## Client Usage
+
+### Sign Up
+
+```ts
+import { authClient } from "@/lib/auth-client";
+
+const { data, error } = await authClient.signUp.email({
+  email: "user@example.com",
+  password: "securePassword123",
+  name: "John Doe",
+  image: "https://example.com/avatar.jpg", // optional
+  callbackURL: "/dashboard" // optional
+}, {
+  onSuccess: (ctx) => {
+    // ctx.data contains user and session
+    console.log("User created:", ctx.data.user);
+  },
+  onError: (ctx) => {
+    alert(ctx.error.message);
+  }
+});
+```
+
+### Sign In
+
+```ts
+const { data, error } = await authClient.signIn.email({
+  email: "user@example.com",
+  password: "securePassword123",
+  callbackURL: "/dashboard",
+  rememberMe: true // default: true
+}, {
+  onSuccess: () => {
+    // redirect or update UI
+  },
+  onError: (ctx) => {
+    console.error(ctx.error.message);
+  }
+});
+```
+
+### Sign Out
+
+```ts
+await authClient.signOut({
+  fetchOptions: {
+    onSuccess: () => {
+      router.push("/login");
+    }
+  }
+});
+```
+
+## Email Verification
+
+### Server Setup
+
+```ts
+export const auth = betterAuth({
+  emailVerification: {
+    sendVerificationEmail: async ({ user, url, token }) => {
+      // Send verification email
+      await sendEmail({
+        to: user.email,
+        subject: "Verify your email",
+        html: `Click <a href="${url}">here</a> to verify your email.`
+      });
+    },
+    sendOnSignUp: true, // Send verification email on signup
+    autoSignInAfterVerification: true // Auto sign-in after verification
+  },
+  emailAndPassword: {
+    enabled: true,
+    requireEmailVerification: true // Require verification before login
+  }
+});
+```
+
+### Client Usage
+
+```ts
+// Send verification email
+await authClient.sendVerificationEmail({
+  email: "user@example.com",
+  callbackURL: "/verify-success"
+});
+
+// Verify email with token
+await authClient.verifyEmail({
+  token: "verification-token-from-email"
+});
+```
+
+## Password Reset Flow
+
+### Server Setup
+
+```ts
+export const auth = betterAuth({
+  emailAndPassword: {
+    enabled: true,
+    sendResetPasswordToken: async ({ user, url, token }) => {
+      await sendEmail({
+        to: user.email,
+        subject: "Reset your password",
+        html: `Click <a href="${url}">here</a> to reset your password.`
+      });
+    }
+  }
+});
+```
+
+### Client Flow
+
+```ts
+// Step 1: Request password reset
+await authClient.forgetPassword({
+  email: "user@example.com",
+  redirectTo: "/reset-password"
+});
+
+// Step 2: Reset password with token
+await authClient.resetPassword({
+  token: "reset-token-from-email",
+  password: "newSecurePassword123"
+});
+```
+
+### Change Password (Authenticated)
+
+```ts
+await authClient.changePassword({
+  currentPassword: "oldPassword123",
+  newPassword: "newPassword456",
+  revokeOtherSessions: true // Optional: logout other sessions
+});
+```
+
+## Username Authentication
+
+Requires `username` plugin for username-based auth.
+
+### Server Setup
+
+```ts
+import { betterAuth } from "better-auth";
+import { username } from "better-auth/plugins";
+
+export const auth = betterAuth({
+  plugins: [
+    username({
+      // Allow sign in with username or email
+      allowUsernameOrEmail: true
+    })
+  ]
+});
+```
+
+### Client Setup
+
+```ts
+import { createAuthClient } from "better-auth/client";
+import { usernameClient } from "better-auth/client/plugins";
+
+export const authClient = createAuthClient({
+  plugins: [usernameClient()]
+});
+```
+
+### Client Usage
+
+```ts
+// Sign up with username
+await authClient.signUp.username({
+  username: "johndoe",
+  password: "securePassword123",
+  email: "john@example.com", // optional
+  name: "John Doe"
+});
+
+// Sign in with username
+await authClient.signIn.username({
+  username: "johndoe",
+  password: "securePassword123"
+});
+
+// Sign in with username or email (if allowUsernameOrEmail: true)
+await authClient.signIn.username({
+  username: "johndoe", // or "john@example.com"
+  password: "securePassword123"
+});
+```
+
+## Framework Setup
+
+### 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);
+```
+
+### Next.js (Pages Router)
+
+```ts
+// pages/api/auth/[...all].ts
+import { auth } from "@/lib/auth";
+import { toNextJsHandler } from "better-auth/next-js";
+
+export default toNextJsHandler(auth);
+```
+
+### Nuxt
+
+```ts
+// server/api/auth/[...all].ts
+import { auth } from "~/utils/auth";
+import { toWebRequest } from "better-auth/utils/web";
+
+export default defineEventHandler((event) => {
+  return auth.handler(toWebRequest(event));
+});
+```
+
+### SvelteKit
+
+```ts
+// hooks.server.ts
+import { auth } from "$lib/auth";
+import { svelteKitHandler } from "better-auth/svelte-kit";
+
+export async function handle({ event, resolve }) {
+  return svelteKitHandler({ event, resolve, auth });
+}
+```
+
+### Astro
+
+```ts
+// pages/api/auth/[...all].ts
+import { auth } from "@/lib/auth";
+
+export async function ALL({ request }: { request: Request }) {
+  return auth.handler(request);
+}
+```
+
+### Hono
+
+```ts
+import { Hono } from "hono";
+import { auth } from "./auth";
+
+const app = new Hono();
+
+app.on(["POST", "GET"], "/api/auth/*", (c) => {
+  return auth.handler(c.req.raw);
+});
+```
+
+### Express
+
+```ts
+import express from "express";
+import { toNodeHandler } from "better-auth/node";
+import { auth } from "./auth";
+
+const app = express();
+
+app.all("/api/auth/*", toNodeHandler(auth));
+```
+
+## Protected Routes
+
+### Next.js Middleware
+
+```ts
+// middleware.ts
+import { auth } from "@/lib/auth";
+import { NextRequest, NextResponse } from "next/server";
+
+export async function middleware(request: NextRequest) {
+  const session = await auth.api.getSession({
+    headers: request.headers
+  });
+
+  if (!session) {
+    return NextResponse.redirect(new URL("/login", request.url));
+  }
+
+  return NextResponse.next();
+}
+
+export const config = {
+  matcher: ["/dashboard/:path*", "/profile/:path*"]
+};
+```
+
+### SvelteKit Hooks
+
+```ts
+// hooks.server.ts
+import { auth } from "$lib/auth";
+import { redirect } from "@sveltejs/kit";
+
+export async function handle({ event, resolve }) {
+  const session = await auth.api.getSession({
+    headers: event.request.headers
+  });
+
+  if (event.url.pathname.startsWith("/dashboard") && !session) {
+    throw redirect(303, "/login");
+  }
+
+  return resolve(event);
+}
+```
+
+### Nuxt Middleware
+
+```ts
+// middleware/auth.ts
+export default defineNuxtRouteMiddleware(async (to) => {
+  const { data: session } = await useAuthSession();
+
+  if (!session.value && to.path.startsWith("/dashboard")) {
+    return navigateTo("/login");
+  }
+});
+```
+
+## User Profile Management
+
+### Get Current User
+
+```ts
+const { data: session } = await authClient.getSession();
+console.log(session.user);
+```
+
+### Update User Profile
+
+```ts
+await authClient.updateUser({
+  name: "New Name",
+  image: "https://example.com/new-avatar.jpg",
+  // Custom fields if defined in schema
+});
+```
+
+### Delete User Account
+
+```ts
+await authClient.deleteUser({
+  password: "currentPassword", // Required for security
+  callbackURL: "/" // Redirect after deletion
+});
+```
+
+## Best Practices
+
+1. **Password Security**: Enforce strong password requirements
+2. **Email Verification**: Enable for production to prevent spam
+3. **Rate Limiting**: Prevent brute force attacks (see advanced-features.md)
+4. **HTTPS**: Always use HTTPS in production
+5. **Error Messages**: Don't reveal if email exists during login
+6. **Session Security**: Use secure, httpOnly cookies
+7. **CSRF Protection**: Better Auth handles this automatically
+8. **Password Reset**: Set short expiration for reset tokens
+9. **Account Lockout**: Consider implementing after N failed attempts
+10. **Audit Logs**: Track auth events for security monitoring