Clerk Hello World

Overview

Make your first authenticated requests using Clerk across server components, client components, API routes, and server actions. Validates your Clerk integration end-to-end.

Prerequisites

• Clerk SDK installed (clerk-install-auth completed)
• Environment variables configured (NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY, CLERK_SECRET_KEY)
• ClerkProvider wrapping application root
• Middleware configured at project root

Instructions

Step 1: Server Component — auth() and currentUser()

// app/dashboard/page.tsx
import { auth, currentUser } from '@clerk/nextjs/server'
import { redirect } from 'next/navigation'

export default async function DashboardPage() {
  // auth() is lightweight — reads JWT from the session cookie, no API call
  const { userId } = await auth()

  if (!userId) redirect('/sign-in')

  // currentUser() makes a Backend API call — use sparingly, counts toward rate limit
  const user = await currentUser()

  return (
    <div>
      <h1>Hello, {user?.firstName || 'User'}!</h1>
      <p>User ID: {userId}</p>
      <p>Email: {user?.emailAddresses[0]?.emailAddress}</p>
      <p>Created: {user?.createdAt ? new Date(user.createdAt).toLocaleDateString() : 'N/A'}</p>
    </div>
  )
}

Key distinction: auth() is cheap (JWT parsing, no network). currentUser() is expensive (Backend API call, rate-limited). Prefer auth() when you only need userId, orgId, or sessionClaims.

Step 2: Protected API Route

// app/api/hello/route.ts
import { auth } from '@clerk/nextjs/server'

export async function GET() {
  const { userId, orgId, sessionClaims } = await auth()

  if (!userId) {
    return Response.json({ error: 'Unauthorized' }, { status: 401 })
  }

  return Response.json({
    message: 'Hello from Clerk!',
    userId,
    orgId: orgId || null,
    sessionId: sessionClaims?.sid,
    timestamp: new Date().toISOString(),
  })
}