Protect content and read user data
Clerk provides a set of hooks and helpers that you can use to protect content and read user data in your Next.js application. Here are examples of how to use these helpers in both the client and server-side to get you started.
Server-side
App Router
auth() and currentUser() are App Router-specific helpers that you can use inside of your Route Handlers, Middleware, Server Components, and Server Actions.
- The
auth()helper will return the Auth object of the currently active user. - The
currentUser()helper will return the Backend User object of the currently active user, which includes helpful information like the user's name or email address. It does count towards the Backend API request rate limit so it's recommended to use the useUser() hook on the client side when possible and only usecurrentUser()when you specifically need user data in a server context. For more information on this helper, see the currentUser() reference.
The following example uses the auth() helper to validate an authenticated user and the currentUser() helper to access the Backend User object for the authenticated user.
import { auth, currentUser } from '@clerk/nextjs/server'
export default async function Page() {
// Use `auth()` to access `isAuthenticated` - if false, the user is not signed in
const { isAuthenticated } = await auth()
// Protect the route by checking if the user is signed in
if (!isAuthenticated) {
return <div>Sign in to view this page</div>
}
// Get the Backend User object when you need access to the user's information
const user = await currentUser()
// Use `user` to render user details or create UI elements
return <div>Welcome, {user.firstName}!</div>
}import { NextResponse } from 'next/server'
import { currentUser, auth } from '@clerk/nextjs/server'
export async function GET() {
// Use `auth()` to access `isAuthenticated` - if false, the user is not signed in
const { isAuthenticated } = await auth()
// Protect the route by checking if the user is signed in
if (!isAuthenticated) {
return new NextResponse('Unauthorized', { status: 401 })
}
// Use `currentUser()` to get the Backend User object
const user = await currentUser()
// Add your Route Handler's logic with the returned `user` object
return NextResponse.json(
{ userId: user.id, email: user.emailAddresses[0].emailAddress },
{ status: 200 },
)
}Pages Router
For Next.js applications using the Pages Router, the getAuth() helper will return the Auth object of the currently active user, which contains important information like the current user's session ID, user ID, and Organization ID, as well as the isAuthenticated property which can be used to protect your API routes.
In some cases, you may need the full Backend User object of the currently active user. This is helpful if you want to render information, like their first and last name, directly from the server.
The clerkClient() helper returns an instance of the JS Backend SDK, which exposes Clerk's Backend API resources through methods such as the getUser() method. This method returns the full Backend User object. It does count towards the Backend API request rate limit so it's recommended to use the useUser() hook on the client side when possible and only use getUser() when you specifically need user data in a server context.
In the following example, the userId is passed to the JS Backend SDK's getUser() method to get the user's full Backend User object.
import { getAuth, clerkClient } from '@clerk/nextjs/server'
import type { NextApiRequest, NextApiResponse } from 'next'
export default async function handler(req: NextApiRequest, res: NextApiResponse) {
// Use `getAuth()` to access `isAuthenticated` and the user's ID
const { isAuthenticated, userId } = getAuth(req)
// Protect the route by checking if the user is signed in
if (!isAuthenticated) {
return res.status(401).json({ error: 'Unauthorized' })
}
// Initialize the JS Backend SDK
const client = await clerkClient()
// Get the user's full Backend User object
const user = await client.users.getUser(userId)
return res.status(200).json({ user })
}The buildClerkProps() function is used in your Next.js application's getServerSideProps to pass authentication state from the server to the client. It returns props that get spread into the <ClerkProvider> component. This enables Clerk's client-side helpers, such as useAuth(), to correctly determine the user's authentication status during server-side rendering.
import { getAuth, buildClerkProps } from '@clerk/nextjs/server'
import { GetServerSideProps } from 'next'
export const getServerSideProps: GetServerSideProps = async (ctx) => {
// Use `getAuth()` to access `isAuthenticated` and the user's ID
const { isAuthenticated, userId } = getAuth(ctx.req)
// Protect the route by checking if the user is signed in
if (!isAuthenticated) {
return {
redirect: {
destination: '/sign-in',
permanent: false,
},
}
}
// Initialize the JS Backend SDK
const client = await clerkClient()
// Get the user's full `Backend User` object
const user = await client.users.getUser(userId)
// Pass the `user` object to buildClerkProps()
return { props: { ...buildClerkProps(ctx.req, { user }) } }
}Client-side
useAuth()
The following example uses the useAuth() hook to access the current auth state, as well as helper methods to manage the current session.
export default function Example() {
const { isLoaded, isSignedIn, userId, sessionId, getToken } = useAuth()
const fetchExternalData = async () => {
// Use `getToken()` to get the current user's session token
const token = await getToken()
// Use `token` to fetch data from an external API
const response = await fetch('https://api.example.com/data', {
headers: {
Authorization: `Bearer ${token}`,
},
})
return response.json()
}
// Use `isLoaded` to check if Clerk is loaded
if (!isLoaded) {
return <div>Loading...</div>
}
// Use `isSignedIn` to check if the user is signed in
if (!isSignedIn) {
// You could also add a redirect to the sign-in page here
return <div>Sign in to view this page</div>
}
return (
<div>
Hello, {userId}! Your current active session is {sessionId}.
</div>
)
}useUser()
The following example uses the useUser() hook to access the User object, which contains the current user's data such as their full name. The following example demonstrates how to use useUser() to check if the user is signed in and display their first name.
export default function Example() {
const { isSignedIn, user, isLoaded } = useUser()
// Use `isLoaded` to check if Clerk is loaded
if (!isLoaded) {
return <div>Loading...</div>
}
// Use `isSignedIn` to protect the content
if (!isSignedIn) {
return <div>Sign in to view this page</div>
}
// Use `user` to access the current user's data
return <div>Hello {user.firstName}!</div>
}Feedback
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