clerk-nextjs-skills

Included with Lifetime

$97 forever

Clerk authentication for Next.js 16 (App Router only) with proxy.ts setup, migration from middleware.ts, environment configuration, and MCP server integration.

Web Devscripts

What this skill does


## Links

- [Clerk Next.js Quickstart](https://clerk.com/docs/nextjs/getting-started/quickstart)
- [Clerk MCP Server Guide](https://clerk.com/docs/nextjs/guides/ai/mcp/build-mcp-server)
- [Clerk Next.js SDK Reference](https://clerk.com/docs/reference/nextjs/overview)
- [clerkMiddleware() Reference](https://clerk.com/docs/reference/nextjs/clerk-middleware)
- [Reading User Data](https://clerk.com/docs/nextjs/guides/users/reading)
- [Protecting Routes](https://clerk.com/docs/reference/nextjs/clerk-middleware)
- [OAuth Token Verification](https://clerk.com/docs/nextjs/guides/development/verifying-oauth-access-tokens)
- [Clerk Dashboard](https://dashboard.clerk.com/)
- [@vercel/mcp-adapter](https://github.com/vercel/mcp-adapter)
- [@clerk/mcp-tools](https://github.com/clerk/mcp-tools)
- [MCP Example Repository](https://github.com/clerk/mcp-nextjs-example)

## Quick Start

### 1. Install Dependencies (Using pnpm)

```bash
pnpm add @clerk/nextjs
# For MCP server integration, also install:
pnpm add @vercel/mcp-adapter @clerk/mcp-tools
```

### 2. Create proxy.ts (Next.js 16)

The `proxy.ts` file replaces `middleware.ts` from Next.js 15. Create it at the root or in `/src`:

```typescript
// proxy.ts (or src/proxy.ts)
import { clerkMiddleware } from '@clerk/nextjs/server'

export default clerkMiddleware()

export const config = {
  matcher: [
    '/((?!_next|[^?]*\\.(?:html?|css|js(?!on)|jpe?g|webp|png|gif|svg|ttf|woff2?|ico|csv|docx?|xlsx?|zip|webmanifest)).*)',
    '/(api|trpc)(.*)',
  ],
}
```

### 3. Set Environment Variables

Create `.env.local` in your project root:

```env
NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY=your_publishable_key_here
CLERK_SECRET_KEY=your_secret_key_here
NEXT_PUBLIC_CLERK_SIGN_IN_URL=/sign-in
NEXT_PUBLIC_CLERK_SIGN_UP_URL=/sign-up
NEXT_PUBLIC_CLERK_AFTER_SIGN_IN_URL=/
NEXT_PUBLIC_CLERK_AFTER_SIGN_UP_URL=/
```

### 4. Add ClerkProvider to Layout

```typescript
// app/layout.tsx
import {
  ClerkProvider,
  SignInButton,
  SignUpButton,
  SignedIn,
  SignedOut,
  UserButton,
} from '@clerk/nextjs'
import type { Metadata } from 'next'

export const metadata: Metadata = {
  title: 'My App',
}

export default function RootLayout({
  children,
}: {
  children: React.ReactNode
}) {
  return (
    <ClerkProvider>
      <html lang="en">
        <body>
          <header className="flex justify-end items-center p-4 gap-4 h-16">
            <SignedOut>
              <SignInButton />
              <SignUpButton />
            </SignedOut>
            <SignedIn>
              <UserButton />
            </SignedIn>
          </header>
          {children}
        </body>
      </html>
    </ClerkProvider>
  )
}
```

### 5. Run Your App

```bash
pnpm dev
```

Visit `http://localhost:3000` and click "Sign Up" to create your first user.

## Key Concepts

### proxy.ts vs middleware.ts

- **Next.js 16 (App Router)**: Use `proxy.ts` for Clerk middleware
- **Next.js ≤15**: Use `middleware.ts` with identical code (filename only differs)
- Clerk's `clerkMiddleware()` function is the same regardless of filename
- The `matcher` configuration ensures proper route handling and performance

### Protecting Routes

By default, `clerkMiddleware()` does not protect routes—all are public. Use `auth.protect()` to require authentication:

```typescript
// Protect specific route
import { auth } from '@clerk/nextjs/server'

export default async function Page() {
  const { userId } = await auth()
  
  if (!userId) {
    // Redirect handled by clerkMiddleware
  }
  
  return <div>Protected content for {userId}</div>
}
```

Or protect all routes in `proxy.ts`:

```typescript
import { clerkMiddleware } from '@clerk/nextjs/server'

export default clerkMiddleware(async (auth, req) => {
  await auth.protect()
})
```

### Environment Variable Validation

Check for required Clerk keys before runtime:

```typescript
// lib/clerk-config.ts
export function validateClerkEnv() {
  const required = [
    'NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY',
    'CLERK_SECRET_KEY',
  ]
  
  const missing = required.filter(key => !process.env[key])
  
  if (missing.length > 0) {
    throw new Error(`Missing required Clerk environment variables: ${missing.join(', ')}`)
  }
}
```

### Accessing User Data

Use Clerk hooks in client components:

```typescript
// app/components/user-profile.tsx
'use client'

import { useUser } from '@clerk/nextjs'

export function UserProfile() {
  const { user, isLoaded } = useUser()
  
  if (!isLoaded) return <div>Loading...</div>
  
  if (!user) return <div>Not signed in</div>
  
  return (
    <div>
      <h1>{user.fullName}</h1>
      <p>{user.primaryEmailAddress?.emailAddress}</p>
    </div>
  )
}
```

Or in server components/actions:

```typescript
// app/actions.ts
'use server'

import { auth, clerkClient } from '@clerk/nextjs/server'

export async function getUserData() {
  const { userId } = await auth()
  
  if (!userId) {
    throw new Error('Unauthorized')
  }
  
  const clerk = await clerkClient()
  const user = await clerk.users.getUser(userId)
  
  return user
}
```

## Migrating from middleware.ts (Next.js 15) to proxy.ts (Next.js 16)

### Step-by-Step Migration

1. **Rename the file** from `middleware.ts` to `proxy.ts` (location remains same: root or `/src`)

2. **Keep the code identical** - No functional changes needed:
   ```typescript
   // Before (middleware.ts)
   import { clerkMiddleware } from '@clerk/nextjs/server'
   export default clerkMiddleware()
   export const config = { ... }
   
   // After (proxy.ts) - Same code
   import { clerkMiddleware } from '@clerk/nextjs/server'
   export default clerkMiddleware()
   export const config = { ... }
   ```

3. **Update Next.js version**:
   ```bash
   pnpm add next@latest
   ```

4. **Verify environment variables** are still in `.env.local` (no changes needed)

5. **Test the migration**:
   ```bash
   pnpm dev
   ```

### Troubleshooting Migration

- If routes aren't protected, ensure `proxy.ts` is in the correct location (root or `/src`)
- Check that `.env.local` has all required Clerk keys
- Clear `.next` cache if middleware changes don't take effect: `rm -rf .next && pnpm dev`
- Verify Next.js version is 16.0+: `pnpm list next`

## Building an MCP Server with Clerk

See [CLERK_MCP_SERVER_SETUP.md](references/CLERK_MCP_SERVER_SETUP.md) for complete MCP server integration.

### Quick MCP Setup Summary

1. **Install MCP dependencies**:
   ```bash
   pnpm add @vercel/mcp-adapter @clerk/mcp-tools
   ```

2. **Create MCP route** at `app/[transport]/route.ts`:
   ```typescript
   import { verifyClerkToken } from '@clerk/mcp-tools/next'
   import { createMcpHandler, withMcpAuth } from '@vercel/mcp-adapter'
   import { auth, clerkClient } from '@clerk/nextjs/server'
   
   const clerk = await clerkClient()
   
   const handler = createMcpHandler((server) => {
     server.tool(
       'get-clerk-user-data',
       'Gets data about the Clerk user that authorized this request',
       {},
       async (_, { authInfo }) => {
         const userId = authInfo!.extra!.userId! as string
         const userData = await clerk.users.getUser(userId)
         return {
           content: [{ type: 'text', text: JSON.stringify(userData) }],
         }
       },
     )
   })
   
   const authHandler = withMcpAuth(
     handler,
     async (_, token) => {
       const clerkAuth = await auth({ acceptsToken: 'oauth_token' })
       return verifyClerkToken(clerkAuth, token)
     },
     {
       required: true,
       resourceMetadataPath: '/.well-known/oauth-protected-resource/mcp',
     },
   )
   
   export { authHandler as GET, authHandler as POST }
   ```

3. **Expose OAuth metadata endpoints** (see references for complete setup)

4. **Update proxy.ts** to exclude `.well-known` endpoints:
   ```typescript
   import { clerkMiddleware, createRouteMatcher } from '@clerk/nextjs/server'
   
   const isPublicRoute = createRouteMatcher([
     '/.well-known/oauth-authorization-server(.*)',
     '/.well-known/oauth-protected-resource(.*

Files: 9

Size: 80.1 KB

Complexity: 66/100

Category: Web Dev

Source: https://github.com/gocallum/nextjs16-agent-skills/tree/main/skills/clerk-nextjs-skills

Related in Web Dev

generating-lwc-components

Included

Lightning Web Components with PICKLES methodology and 165-point scoring. Use this skill when the user creates or edits LWC components, builds wire service patterns, or writes Jest tests for LWC. TRIGGER when: user creates/edits LWC components, touches lwc/**/*.js, .html, .css, .js-meta.xml files, or asks about wire service, SLDS, or Jest LWC tests. DO NOT TRIGGER when: Apex classes (use generating-apex), Aura components, or Visualforce.

Web Devscripts

tanstack-query

Included

Manage server state in React with TanStack Query v5. Set up queries with useQuery, mutations with useMutation, configure QueryClient caching strategies, implement optimistic updates, and handle infinite scroll with useInfiniteQuery. Use when: setting up data fetching in React projects, migrating from v4 to v5, or fixing object syntax required errors, query callbacks removed issues, cacheTime renamed to gcTime, isPending vs isLoading confusion, keepPreviousData removed problems.

Web Devscripts

document-processor-api

Included

Process documents with Nutrient DWS. Use when the user wants to generate PDFs from HTML or URLs, convert Office/images/PDFs, assemble or split packets, OCR scans, extract text/tables/key-value pairs, redact PII, watermark, sign, fill forms, optimize PDFs, or produce compliance outputs like PDF/A or PDF/UA. Triggers include convert to PDF, merge these PDFs, OCR this scan, extract tables, redact PII, sign this PDF, make this PDF/A, or linearize for web delivery.

Web Devscripts

nutrient-document-processing

Included

Web Devscripts

tanstack-query

Included

Manage server state in React with TanStack Query v5. Covers useMutationState, simplified optimistic updates, throwOnError, network mode (offline/PWA), and infiniteQueryOptions. Use when setting up data fetching, fixing v4→v5 migration errors (object syntax, gcTime, isPending, keepPreviousData), or debugging SSR/hydration issues with streaming server components.

Web Devscripts

accelint-nextjs-best-practices

Included

Next.js performance optimization and best practices. Use when writing Next.js code (App Router or Pages Router); implementing Server Components, Server Actions, or API routes; optimizing RSC serialization, data fetching, or server-side rendering; reviewing Next.js code for performance issues; fixing authentication in Server Actions; or implementing Suspense boundaries, parallel data fetching, or request deduplication.

Web Devscripts