Skill

clerk-react-patterns

Name: clerk-react-patterns
Author: Clerk

implement Clerk auth in React SPAs

Published by Clerk Updated Apr 7

Covers Security React Clerk Authentication Frontend

Description

React SPA auth patterns with @clerk/react for Vite/CRA - ClerkProvider setup, useAuth/useUser/useClerk hooks, React Router protected routes, custom sign-in flows. Triggers on: Vite Clerk setup, React Router auth, useAuth hook, protected route, custom sign-in form React.

SKILL.md

React SPA Patterns

This skill covers @clerk/react for Vite/CRA SPAs. For Next.js use clerk-nextjs-patterns. For TanStack Start use clerk-tanstack-patterns.

What Do You Need?

Task	Reference
useAuth / useUser / useClerk hooks	references/hooks.md
Protected routes with React Router	references/protected-routes.md
Custom sign-in / sign-up forms	references/custom-flows.md
React Router v6/v7 integration	references/router-integration.md

References

Reference	Description
`references/hooks.md`	useAuth, isLoaded guard
`references/protected-routes.md`	ProtectedRoute pattern
`references/custom-flows.md`	useSignIn, useSignUp flows
`references/router-integration.md`	React Router v6/v7 setup

Setup

npm install @clerk/react

.env:

VITE_CLERK_PUBLISHABLE_KEY=pk_...

src/main.tsx:

import { StrictMode } from 'react'
import { createRoot } from 'react-dom/client'
import { ClerkProvider } from '@clerk/react'
import App from './App.tsx'

const PUBLISHABLE_KEY = import.meta.env.VITE_CLERK_PUBLISHABLE_KEY

createRoot(document.getElementById('root')!).render(
  <StrictMode>
    <ClerkProvider publishableKey={PUBLISHABLE_KEY}>
      <App />
    </ClerkProvider>
  </StrictMode>,
)

Mental Model

@clerk/react is client-only — there is no server-side auth(). All auth state comes from hooks.

isLoaded must be true before trusting isSignedIn — always guard on isLoaded
useClerk() gives access to signOut, openSignIn, openUserProfile and other methods
getToken() from useAuth() fetches the session JWT for API calls

Minimal Pattern

import { useAuth } from '@clerk/react'

export function Dashboard() {
  const { isLoaded, isSignedIn, userId } = useAuth()

  if (!isLoaded) return <div>Loading...</div>
  if (!isSignedIn) return <div>Please sign in</div>

  return <div>Hello {userId}</div>
}

Protected Route (React Router v6/v7)

import { Navigate, Outlet } from 'react-router-dom'
import { useAuth } from '@clerk/react'

export function ProtectedRoute() {
  const { isLoaded, isSignedIn } = useAuth()

  if (!isLoaded) return <div>Loading...</div>
  if (!isSignedIn) return <Navigate to="/sign-in" replace />

  return <Outlet />
}

<Routes>
  <Route element={<ProtectedRoute />}>
    <Route path="/dashboard" element={<Dashboard />} />
    <Route path="/settings" element={<Settings />} />
  </Route>
  <Route path="/sign-in" element={<SignIn />} />
</Routes>

Token for API Calls

import { useAuth } from '@clerk/react'

export function DataFetcher() {
  const { getToken } = useAuth()

  async function fetchData() {
    const token = await getToken()
    if (!token) return

    const res = await fetch('/api/data', {
      headers: { Authorization: `Bearer ${token}` },
    })
    return res.json()
  }

  return <button onClick={fetchData}>Load</button>
}

Common Pitfalls

Symptom	Cause	Fix
`isSignedIn` is `undefined`	`isLoaded` is still `false`	Always check `isLoaded` first
`ClerkProvider` missing	Provider not at root	Wrap `<App>` in `main.tsx`
Env var undefined	Wrong Vite prefix	Use `VITE_CLERK_PUBLISHABLE_KEY`, access via `import.meta.env`
Token is `null`	User not signed in	Null-check `getToken()` result
Sign-in component shows blank	No `publishableKey` on provider	Pass `publishableKey` explicitly

Docs

React SDK

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