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

See Also

• clerk-setup - Initial Clerk install
• clerk-custom-ui - Custom flows & appearance
• clerk-orgs - B2B organizations

Docs

React SDK