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Cloudflare Turnstile

This skill should be used when the user asks to \"add turnstile\", \"implement bot protection\", \"validate turnstile token\", \"fix turnstile error\", \"setup captcha alternative\", or encounters error codes 100*/300*/600*, CSP errors, or token validation failures. Provides CAP…

reactcloudflareai
By secondsky

Skill Content

# Cloudflare Turnstile

**Status**: Production Ready ✅ | **Last Verified**: 2025-11-26

**Dependencies**: None (optional: @marsidev/react-turnstile for React)

**Contents**: [Quick Start](#quick-start-10-minutes) • [Critical Rules](#critical-rules) • [Top 12 Errors](#known-issues-prevention) • [Common Patterns](#common-patterns) • [When to Load References](#when-to-load-references) • [Troubleshooting](#troubleshooting)

---

## Quick Start (10 Minutes)

### 1. Create Turnstile Widget

Get your sitekey and secret key from Cloudflare Dashboard.

```bash
# Navigate to: https://dash.cloudflare.com/?to=/:account/turnstile
# Create new widget → Copy sitekey (public) and secret key (private)
```

**Why this matters:**
- Each widget has unique sitekey/secret pair
- Sitekey goes in frontend (public)
- Secret key ONLY in backend (private)
- Use different widgets for dev/staging/production

### 2. Add Widget to Frontend

Embed the Turnstile widget in your HTML form.

```html
<!DOCTYPE html>
<html>
<head>
  <script src="https://challenges.cloudflare.com/turnstile/v0/api.js" async defer></script>
</head>
<body>
  <form id="myForm" action="/submit" method="POST">
    <input type="email" name="email" required>
    <!-- Turnstile widget renders here -->
    <div class="cf-turnstile" data-sitekey="YOUR_SITE_KEY"></div>
    <button type="submit">Submit</button>
  </form>
</body>
</html>
```

**CRITICAL:**
- Never proxy or cache `api.js` - must load from Cloudflare CDN
- Widget auto-creates hidden input `cf-turnstile-response` with token
- Token expires in 5 minutes
- Each token is single-use only

### 3. Validate Token on Server

ALWAYS validate the token server-side. Client-side verification alone is not secure.

```typescript
// Cloudflare Workers example
export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const formData = await request.formData()
    const token = formData.get('cf-turnstile-response')
    const ip = request.headers.get('CF-Connecting-IP')

    // Validate token with Siteverify API
    const verifyFormData = new FormData()
    verifyFormData.append('secret', env.TURNSTILE_SECRET_KEY)
    verifyFormData.append('response', token)
    verifyFormData.append('remoteip', ip)

    const result = await fetch(
      'https://challenges.cloudflare.com/turnstile/v0/siteverify',
      {
        method: 'POST',
        body: verifyFormData,
      }
    )

    const outcome = await result.json()

    if (!outcome.success) {
      return new Response('Invalid Turnstile token', { status: 401 })
    }

    // Token valid - proceed with form processing
    return new Response('Success!')
  }
}
```

---

## The 3-Step Setup Process

### Step 1: Create Widget Configuration

1. Log into Cloudflare Dashboard
2. Navigate to Turnstile section
3. Click "Add Site"
4. Configure:
   - **Widget Mode**: Managed (recommended), Non-Interactive, or Invisible
   - **Domains**: Add allowed hostnames (e.g., example.com, localhost for dev)
   - **Name**: Descriptive name (e.g., "Production Login Form")

**Key Points:**
- Use separate widgets for dev/staging/production
- Restrict domains to only those you control
- Managed mode provides best balance of security and UX
- localhost must be explicitly added for local testing

### Step 2: Client-Side Integration

Choose between implicit or explicit rendering:

**Implicit Rendering** (Recommended for static forms):
```html
<!-- 1. Load script -->
<script src="https://challenges.cloudflare.com/turnstile/v0/api.js" async defer></script>

<!-- 2. Add widget -->
<div class="cf-turnstile"
     data-sitekey="YOUR_SITE_KEY"
     data-callback="onSuccess"
     data-error-callback="onError"></div>

<script>
function onSuccess(token) {
  console.log('Turnstile success:', token)
}

function onError(error) {
  console.error('Turnstile error:', error)
}
</script>
```

**Explicit Rendering** (For SPAs/dynamic UIs):
```typescript
// 1. Load script with explicit mode
<script src="https://challenges.cloudflare.com/turnstile/v0/api.js?render=explicit" defer></script>

// 2. Render programmatically
const widgetId = turnstile.render('#container', {
  sitekey: 'YOUR_SITE_KEY',
  callback: (token) => {
    console.log('Token:', token)
  },
  'error-callback': (error) => {
    console.error('Error:', error)
  },
  theme: 'auto',
  execution: 'render', // or 'execute' for manual trigger
})

// Control lifecycle
turnstile.reset(widgetId)        // Reset widget
turnstile.remove(widgetId)       // Remove widget
turnstile.execute(widgetId)      // Manually trigger challenge
const token = turnstile.getResponse(widgetId) // Get current token
```

**React Integration** (using @marsidev/react-turnstile):
```tsx
import { Turnstile } from '@marsidev/react-turnstile'

export function MyForm() {
  const [token, setToken] = useState<string>()

  return (
    <form>
      <Turnstile
        siteKey={TURNSTILE_SITE_KEY}
        onSuccess={setToken}
        onError={(error) => console.error(error)}
      />
      <button disabled={!token}>Submit</button>
    </form>
  )
}
```

### Step 3: Server-Side Validation

**MANDATORY**: Always call Siteverify API to validate tokens.

```typescript
interface TurnstileResponse {
  success: boolean
  challenge_ts?: string
  hostname?: string
  error-codes?: string[]
  action?: string
  cdata?: string
}

async function validateTurnstile(
  token: string,
  secretKey: string,
  options?: {
    remoteip?: string
    idempotency_key?: string
    expectedAction?: string
    expectedHostname?: string
  }
): Promise<TurnstileResponse> {
  const formData = new FormData()
  formData.append('secret', secretKey)
  formData.append('response', token)

  if (options?.remoteip) {
    formData.append('remoteip', options.remoteip)
  }

  if (options?.idempotency_key) {
    formData.append('idempotency_key', options.idempotency_key)
  }

  const response = await fetch(
    'https://challenges.cloudflare.com/turnstile/v0/siteverify',
    {
      method: 'POST',
      body: formData,
    }
  )

  const result = await response.json<TurnstileResponse>()

  // Additional validation
  if (result.success) {
    if (options?.expectedAction && result.action !== options.expectedAction) {
      return { success: false, 'error-codes': ['action-mismatch'] }
    }

    if (options?.expectedHostname && result.hostname !== options.expectedHostname) {
      return { success: false, 'error-codes': ['hostname-mismatch'] }
    }
  }

  return result
}

// Usage in Cloudflare Worker
const result = await validateTurnstile(
  token,
  env.TURNSTILE_SECRET_KEY,
  {
    remoteip: request.headers.get('CF-Connecting-IP'),
    expectedHostname: 'example.com',
  }
)

if (!result.success) {
  return new Response('Turnstile validation failed', { status: 401 })
}
```

---

## Critical Rules

### Always Do

✅ **Call Siteverify API** - Server-side validation is mandatory
✅ **Use HTTPS** - Never validate over HTTP
✅ **Protect secret keys** - Never expose in frontend code
✅ **Handle token expiration** - Tokens expire after 5 minutes
✅ **Implement error callbacks** - Handle failures gracefully
✅ **Use dummy keys for testing** - Test sitekey: `1x00000000000000000000AA`
✅ **Set reasonable timeouts** - Don't wait indefinitely for validation
✅ **Validate action/hostname** - Check additional fields when specified
✅ **Rotate keys periodically** - Use dashboard or API to rotate secrets
✅ **Monitor analytics** - Track solve rates and failures
✅ **Validate token AFTER form submission** - Verify tokens after user completes form, not before. Premature validation creates security vulnerabilities where attackers obtain valid tokens then bypass protection

### Never Do

❌ **Skip server validation** - Client-side only = security vulnerability
❌ **Proxy api.js script** - Must load from Cloudflare CDN
❌ **Reuse tokens** - Each token is single-use only
❌ **Use GET requests** - Siteverify only accepts POST
❌ **Expose secret key** - Keep secrets in backend environment only
❌ **Trust client-side validation** - Tokens can be forged
❌ **Cache api.js** - Future updates will break your integration
❌ **Use production keys in tests** - Use dummy keys instead
❌ **Ignore error callbacks** - Always handle failures

---

## Known Issues Prevention

This skill prevents **12** documented issues:

### Issue #1: Missing Server-Side Validation
**Error**: Zero token validation in Turnstile Analytics dashboard
**Source**: https://developers.cloudflare.com/turnstile/get-started/
**Why It Happens**: Developers only implement client-side widget, skip Siteverify call
**Prevention**: All templates include mandatory server-side validation with Siteverify API

### Issue #2: Token Expiration (5 Minutes)
**Error**: `success: false` for valid tokens submitted after delay
**Source**: https://developers.cloudflare.com/turnstile/get-started/server-side-validation
**Why It Happens**: Tokens expire 300 seconds after generation
**Prevention**: Templates document TTL and implement token refresh on expiration

### Issue #3: Secret Key Exposed in Frontend
**Error**: Security bypass - attackers can validate their own tokens
**Source**: https://developers.cloudflare.com/turnstile/get-started/server-side-validation
**Why It Happens**: Secret key hardcoded in JavaScript or visible in source
**Prevention**: All templates show backend-only validation with environment variables

### Issue #4: GET Request to Siteverify
**Error**: API returns 405 Method Not Allowed
**Source**: https://developers.cloudflare.com/turnstile/migration/recaptcha
**Why It Happens**: reCAPTCHA supports GET, Turnstile requires POST
**Prevention**: Templates use POST with FormData or JSON body

### Issue #5: Content Security Policy Blocking
**Error**: Error 200500 - "Loading error: The iframe could not be loaded"
**Source**: https://developers.cloudflare.com/turnstile/troubleshooting/client-side-errors/error-codes
**Why It Happens**: CSP blocks challenges.cloudflare.com iframe
**Prevention**: Skill includes CSP configuration reference and check-csp.sh script

### Issue #6: Widget Crash (Error 300030)
**Error**: Generic client execution error for legitimate users
**Source**: https://community.cloudflare.com/t/turnstile-is-frequently-generating-300x-errors/700903
**Why It Happens**: Unknown - appears to be Cloudflare-side issue (2025)
**Prevention**: Templates implement error callbacks, retry logic, and fallback handling

### Issue #7: Configuration Error (Error 600010)
**Error**: Widget fails with "configuration error"
**Source**: https://community.cloudflare.com/t/repeated-cloudflare-turnstile-error-600010/644578
**Why It Happens**: Missing or deleted hostname in widget configuration
**Prevention**: Templates document hostname allowlist requirement and verification steps

### Issue #8: Safari 18 / macOS 15 "Hide IP" Issue
**Error**: Error 300010 when Safari's "Hide IP address" is enabled
**Source**: https://community.cloudflare.com/t/turnstile-is-frequently-generating-300x-errors/700903
**Why It Happens**: Privacy settings interfere with challenge signals
**Prevention**: Error handling reference documents Safari workaround (disable Hide IP)

### Issue #9: Brave Browser Confetti Animation Failure
**Error**: Verification fails during success animation
**Source**: https://github.com/brave/brave-browser/issues/45608 (April 2025)
**Why It Happens**: Brave shields block animation scripts
**Prevention**: Templates handle success before animation completes

### Issue #10: Next.js + Jest Incompatibility
**Error**: @marsidev/react-turnstile breaks Jest tests
**Source**: https://github.com/marsidev/react-turnstile/issues/112 (Oct 2025)
**Why It Happens**: Module resolution issues with Jest
**Prevention**: Testing guide includes Jest mocking patterns and dummy sitekey usage

### Issue #11: localhost Not in Allowlist
**Error**: Error 110200 - "Unknown domain: Domain not allowed"
**Source**: https://developers.cloudflare.com/turnstile/troubleshooting/client-side-errors/error-codes
**Why It Happens**: Production widget used in development without localhost in allowlist
**Prevention**: Templates use dummy test keys for dev, document localhost allowlist requirement

### Issue #12: Token Reuse Attempt
**Error**: `success: false` with "token already spent" error
**Source**: https://developers.cloudflare.com/turnstile/troubleshooting/testing
**Why It Happens**: Each token can only be validated once
**Prevention**: Templates document single-use constraint and token refresh patterns

---

## Configuration

**Wrangler (Workers)**: Load `templates/wrangler-turnstile-config.jsonc` for complete configuration. Key settings: `vars` for public sitekey (safe to commit), `secrets` for private secret key (use `wrangler secret put TURNSTILE_SECRET_KEY`).

**CSP Directives** (if using Content Security Policy):
```html
<meta http-equiv="Content-Security-Policy" content="
  script-src 'self' https://challenges.cloudflare.com;
  frame-src 'self' https://challenges.cloudflare.com;
  connect-src 'self' https://challenges.cloudflare.com;">
```

---

## Common Patterns

**Hono + Cloudflare Workers**: Server-side validation in Workers API routes with Hono framework. Load `references/common-patterns.md` #pattern-1 when building Workers endpoints requiring bot protection.

**React + Next.js**: Client-side forms with @marsidev/react-turnstile integration. Load `references/common-patterns.md` #pattern-2 when integrating Turnstile with React/Next.js applications.

**E2E Testing**: Automated testing with dummy keys (Playwright, Cypress, Jest). Load `references/common-patterns.md` #pattern-3 when writing E2E tests or setting up CI/CD pipelines.

**Widget Lifecycle**: Programmatic widget control for SPAs (render, reset, remove, getToken). Load `references/common-patterns.md` #pattern-4 when building SPAs requiring explicit widget management.

---

## When to Load References

**`references/widget-configs.md`**: Configuring widget appearance, themes, execution modes, size, language, or retry behavior.

**`references/error-codes.md`**: Debugging error codes 100*, 200*, 300*, 400*, 600* or troubleshooting client-side failures (CSP, domain errors, widget crashes).

**`references/testing-guide.md`**: Setting up E2E tests (Playwright, Cypress), local development with dummy keys, or CI/CD pipeline integration.

**`references/react-integration.md`**: Integrating with React, Next.js, or troubleshooting @marsidev/react-turnstile issues (Jest mocking, SSR, hooks).

**`references/common-patterns.md`**: Building Hono Workers routes, React forms, E2E tests, or widget lifecycle management (explicit rendering).

**`references/advanced-topics.md`**: Implementing pre-clearance for SPAs, custom actions/cdata, retry strategies, or multi-widget pages.

**`references/setup-checklist.md`**: Preparing for deployment, verifying complete setup, or ensuring production readiness (14-point checklist).

**`references/migration-guide.md`**: Migrating from reCAPTCHA (v2) or hCaptcha to Turnstile, including compat mode, API differences, and POST-only Siteverify requirement.

**`references/browser-support.md`**: Browser compatibility matrix, Safari 18 "Hide IP" workaround, Brave shields issues, and browser-specific fallbacks.

**`references/mobile-implementation.md`**: WebView integration for iOS, Android, React Native, and Flutter, including User Agent consistency and storage persistence requirements.

**`templates/`**: **wrangler-turnstile-config.jsonc** (Workers env), **turnstile-widget-implicit.html** (static forms), **turnstile-widget-explicit.ts** (SPA rendering), **turnstile-server-validation.ts** (Siteverify API), **turnstile-react-component.tsx** (React integration), **turnstile-hono-route.ts** (Hono validation), **turnstile-test-config.ts** (testing setup)

**`scripts/check-csp.sh`**: Verify Content Security Policy allows Turnstile (usage: `./scripts/check-csp.sh https://example.com`)

---


## Dependencies

**Required**: None (Turnstile loads from Cloudflare CDN)

**Optional**: @marsidev/react-turnstile@1.3.1 (React), turnstile-types@1.2.3 (TypeScript), vue-turnstile (Vue 3), ngx-turnstile (Angular), svelte-turnstile (Svelte), @nuxtjs/turnstile (Nuxt)

---

## Official Documentation

**Turnstile**: https://developers.cloudflare.com/turnstile/ • **Get Started**: https://developers.cloudflare.com/turnstile/get-started/ • **Error Codes**: https://developers.cloudflare.com/turnstile/troubleshooting/client-side-errors/error-codes/ • **Testing**: https://developers.cloudflare.com/turnstile/troubleshooting/testing/ • **Migration (reCAPTCHA)**: https://developers.cloudflare.com/turnstile/migration/recaptcha/ • **MCP**: Use `mcp__cloudflare-docs__search_cloudflare_documentation` tool

---

## Troubleshooting

### Problem: Error 110200 - "Unknown domain"
**Solution**: Add your domain (including localhost for dev) to widget's allowed domains in Cloudflare Dashboard. For local dev, use dummy test sitekey `1x00000000000000000000AA` instead.

### Problem: Error 300030 - Widget crashes for legitimate users
**Solution**: Implement error callback with retry logic. This is a known Cloudflare-side issue (2025). Fallback to alternative verification if retries fail.

### Problem: Tokens always return `success: false`
**Solution**:
1. Check token hasn't expired (5 min TTL)
2. Verify secret key is correct
3. Ensure token hasn't been validated before (single-use)
4. Check hostname matches widget configuration

### Problem: CSP blocking iframe (Error 200500)
**Solution**: Add CSP directives:
```html
<meta http-equiv="Content-Security-Policy" content="
  frame-src https://challenges.cloudflare.com;
  script-src https://challenges.cloudflare.com;
">
```

### Problem: Safari 18 "Hide IP" causing Error 300010
**Solution**: Document in error message that users should disable Safari's "Hide IP address" setting (Safari → Settings → Privacy → Hide IP address → Off)

### Problem: Next.js + Jest tests failing with @marsidev/react-turnstile
**Solution**: Mock the Turnstile component in Jest setup:
```typescript
// jest.setup.ts
jest.mock('@marsidev/react-turnstile', () => ({
  Turnstile: () => <div data-testid="turnstile-mock" />,
}))
```

---

**Token Efficiency**: ~65-70% savings vs manual integration

**Errors Prevented**: 12 documented security/validation issues with complete solutions

**Deployment Checklist**: Load `references/setup-checklist.md` for complete 14-point pre-deployment verification

How to use

  1. Copy the skill content above
  2. Create a .claude/skills directory in your project
  3. Save as .claude/skills/claude-skills-cloudflare-turnstile.md
  4. Use /claude-skills-cloudflare-turnstile in Claude Code to invoke this skill
View source on GitHub

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