> ## Documentation Index
> Fetch the complete documentation index at: https://mf2.dev/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

> User authentication and route protection powered by Clerk.

`@repo/auth` handles sign-in, sign-up, session management, and route protection through [Clerk](https://clerk.com/docs).

## Usage

Check the session in server components:

```ts title="apps/app/page.tsx" theme={null}
import { auth } from "@repo/auth";

export default async function DashboardPage() {
  const session = await auth();

  if (!session.userId) {
    redirect("/sign-in");
  }

  return <Dashboard userId={session.userId} />;
}
```

## Route Protection

Lock down routes in middleware:

```ts title="apps/app/middleware.ts" theme={null}
import { authMiddleware } from "@repo/auth";

export default authMiddleware({
  publicRoutes: ["/", "/sign-in", "/sign-up", "/api/webhook(.*)"],
});
```

## User Sync

Clerk webhooks sync user data to Convex. When a user signs up, updates their profile, or deletes their account, Clerk posts to your Convex HTTP endpoint at `/webhooks/clerk`. The handler validates the webhook signature and upserts or removes the user record.

This gives your Convex queries direct access to user data without extra API calls to Clerk. See the [Convex Provider](/packages/convex#user-sync-via-webhooks) page for the full setup guide.

## Environment Variables

See [Environment Variables: Authentication](/setup/env#1-authentication-clerk).

## Learn More

* [Clerk documentation](https://clerk.com/docs)