Clerk React Patterns

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