Users
You will inevitably build custom components that access the user in one way or another. In this section, we will take a closer look at the functions and hooks that let you do this.
Client Component basics
The useUser() hook returns the current user in a Client Component. By default, it will return null if the user is not signed in.
"use client";
import { useUser } from "@stackframe/stack"
export function MyClientComponent() {
const user = useUser();
return <div>{user ? `Hello, ${user.displayName ?? "anon"}` : 'You are not logged in'}</div>;
}The useUser() hook is simply a shorthand for useStackApp().useUser(). useStackApp() also contains other useful hooks and methods for clients, which will be described later.
Sometimes, you want to retrieve the user only if they're signed in, and redirect to the sign-in page otherwise. In this case, simply pass { or: "redirect" }, and the function will never return null.
const user = useUser({ or: "redirect" });
return <div>{`Hello, ${user.displayName ?? "anon"}`}</div>;Server Component basics
Since useUser() is a stateful hook, you can't use it on server components. Instead, you can import stackServerApp from stack/client.ts and call getUser():
import { stackServerApp } from "@/stack/server";
export default async function MyServerComponent() {
const user = await stackServerApp.getUser(); // or: stackServerApp.getUser({ or: "redirect" })
return <div>{user ? `Hello, ${user.displayName ?? "anon"}` : 'You are not logged in'}</div>;
}Since useUser() is a hook, it will re-render the component on user changes (eg. signout), while getUser() will only fetch the user once (on page load). You can also call useStackApp().getUser() on the client side to get the user in a non-component context.
Protecting a page
There are three ways to protect a page: in Client Components with useUser({ or: "redirect" }), in Server Components with await getUser({ or: "redirect" }), or with middleware.
On Client Components, the useUser({ or: 'redirect' }) hook will redirect the user to the sign-in page if they are not logged in. Similarly, on Server Components, call await getUser({ or: "redirect" }) to protect a page (or component).
Middleware can be used whenever it is easy to tell whether a page should be protected given just the URL, for example, when you have a /private section only accessible to logged-in users.
"use client";
import { useUser } from "@stackframe/stack";
export default function MyProtectedClientComponent() {
useUser({ or: 'redirect' });
return <h1>You can only see this if you are logged in</h1>
}import { stackServerApp } from "@/stack/server";
export default async function MyProtectedServerComponent() {
await stackServerApp.getUser({ or: 'redirect' });
return <h1>You can only see this if you are logged in</h1>
}export async function middleware(request: NextRequest) {
const user = await stackServerApp.getUser();
if (!user) {
return NextResponse.redirect(new URL('/handler/sign-in', request.url));
}
return NextResponse.next();
}
export const config = {
// You can add your own route protection logic here
// Make sure not to protect the root URL, as it would prevent users from accessing static Next.js files or Stack's /handler path
matcher: '/protected/:path*',
};If you have sensitive information hidden in the page HTML itself, be aware of Next.js differences when using Server vs. Client Components.
-
Client Components: Client components are always sent to the browser, regardless of page protection. This is standard Next.js behavior. For more information, please refer to the Next.js documentation.
-
Server Components: If a component is protected, it is guaranteed that its bundled HTML will not be sent to the browser if the user is not logged in. However, this is not necessarily true for its children and the rest of the page, as Next.js may split components on the same page and send them to the client separately for performance.
For example, if your page is
<Parent><Child /></Parent>, whereParentis protected andChildis not, Next.js may still send<Child />to the browser even if the user is not logged in. (Normal browsers will never display it, but attackers may be able to retrieve it.) Notably, this also applies to unprotected pages inside protected layouts.To remediate this, every component/page that contains sensitive information should protect itself, instead of relying on an outer layout. This is good practice anyways; it prevents you from accidentally exposing the data.
-
Middleware: Prior to Next.js v15.2.3, Next.js allowed attackers to see unprotected components if you only protect on a middleware level. Since v15.2.3, this is no longer possible, and you don't have to worry about leaking sensitive information when using middleware to protect a route.
No matter which method you use, attackers will never be able to, say, impersonate a user.
User data
You can update attributes on a user object with the user.update() function.
'use client';
import { useUser } from "@stackframe/stack";
export default function MyClientComponent() {
const user = useUser();
return <button onClick={async () => await user.update({ displayName: "New Name" })}>
Change Name
</button>;
}You can also store custom user data in the clientMetadata, serverMetadata, or clientReadOnlyMetadata fields. More information here.
Signing out
You can sign out the user by redirecting them to /handler/sign-out or simply by calling user.signOut(). They will be redirected to the URL configured as afterSignOut in the StackServerApp.
"use client";
import { useUser } from "@stackframe/stack";
export default function SignOutButton() {
const user = useUser();
return user ? <button onClick={() => user.signOut()}>Sign Out</button> : "Not signed in";
}import { stackServerApp } from "@/stack/server";
export default async function SignOutLink() {
// stackServerApp.urls.signOut is equal to /handler/sign-out
return <a href={stackServerApp.urls.signOut}>Sign Out</a>;
}Example: Custom profile page
Stack automatically creates a user profile on sign-up. Let's build a page that displays this information. In app/profile/page.tsx:
'use client';
import { useUser, useStackApp, UserButton } from "@stackframe/stack";
export default function PageClient() {
const user = useUser();
const app = useStackApp();
return (
<div>
{user ? (
<div>
<UserButton />
<p>Welcome, {user.displayName ?? "unnamed user"}</p>
<p>Your e-mail: {user.primaryEmail}</p>
<button onClick={() => user.signOut()}>Sign Out</button>
</div>
) : (
<div>
<p>You are not logged in</p>
<button onClick={() => app.redirectToSignIn()}>Sign in</button>
<button onClick={() => app.redirectToSignUp()}>Sign up</button>
</div>
)}
</div>
);
}import { stackServerApp } from "@/stack/server";
import { UserButton } from "@stackframe/stack";
export default async function Page() {
const user = await stackServerApp.getUser();
return (
<div>
{user ? (
<div>
<UserButton />
<p>Welcome, {user.displayName ?? "unnamed user"}</p>
<p>Your e-mail: {user.primaryEmail}</p>
<p><a href={stackServerApp.urls.signOut}>Sign Out</a></p>
</div>
) : (
<div>
<p>You are not logged in</p>
<p><a href={stackServerApp.urls.signIn}>Sign in</a></p>
<p><a href={stackServerApp.urls.signUp}>Sign up</a></p>
</div>
)}
</div>
);
}After saving your code, you can see the profile page on http://localhost:3000/profile.
For more examples on how to use the User object, check the the SDK documentation.
Next steps
In the next guide, we will show you how to put your application into production.