name: cloudflare-turnstile description: | Add bot protection with Turnstile (CAPTCHA alternative). Use when: protecting forms, securing login/signup, preventing spam, migrating from reCAPTCHA, integrating with React/Next.js/Hono, implementing E2E tests, or debugging CSP errors, token validation failures, or error codes 100/300/600*.

Cloudflare Turnstile

Status: Production Ready ✅ Last Updated: 2025-11-24 Dependencies: None (optional: @marsidev/react-turnstile for React) Latest Versions: @marsidev/react-turnstile@1.3.1, turnstile-types@1.2.3

Recent Updates (2025):

March 2025: Upgraded Turnstile Analytics with TopN statistics (7 dimensions: hostnames, browsers, countries, user agents, ASNs, OS, source IPs), anomaly detection, enhanced bot behavior monitoring
2025: WCAG 2.1 AA compliance, Free plan (20 widgets, 7-day analytics), Enterprise features (unlimited widgets, ephemeral IDs, any hostname support, 30-day analytics, offlabel branding)

Quick Start (5 Minutes)

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

# 2. Add widget to frontend
<script src="https://challenges.cloudflare.com/turnstile/v0/api.js" async defer></script>
<form>
  <div class="cf-turnstile" data-sitekey="YOUR_SITE_KEY"></div>
  <button type="submit">Submit</button>
</form>

# 3. Validate token server-side (Cloudflare Workers)
const formData = await request.formData()
const token = formData.get('cf-turnstile-response')

const verifyFormData = new FormData()
verifyFormData.append('secret', env.TURNSTILE_SECRET_KEY)
verifyFormData.append('response', token)
verifyFormData.append('remoteip', request.headers.get('CF-Connecting-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', { status: 401 })

CRITICAL:

Token expires in 5 minutes, single-use only
ALWAYS validate server-side (Siteverify API required)
Never proxy/cache api.js (must load from Cloudflare CDN)
Use different widgets for dev/staging/production

Rendering Modes

Implicit (auto-render on page load):

<script src="https://challenges.cloudflare.com/turnstile/v0/api.js" async defer></script>
<div class="cf-turnstile" data-sitekey="YOUR_SITE_KEY" data-callback="onSuccess"></div>

Explicit (programmatic control for SPAs):

<script src="https://challenges.cloudflare.com/turnstile/v0/api.js?render=explicit"></script>
const widgetId = turnstile.render('#container', { sitekey: 'YOUR_SITE_KEY' })
turnstile.reset(widgetId)   // Reset widget
turnstile.getResponse(widgetId)  // Get token

React (using @marsidev/react-turnstile):

import { Turnstile } from '@marsidev/react-turnstile'
<Turnstile siteKey={TURNSTILE_SITE_KEY} onSuccess={setToken} />

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

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.jsonc:

{
  "vars": { "TURNSTILE_SITE_KEY": "1x00000000000000000000AA" },
  "secrets": ["TURNSTILE_SECRET_KEY"]  // Run: wrangler secret put TURNSTILE_SECRET_KEY
}

Required CSP:

<meta http-equiv="Content-Security-Policy" content="
  script-src 'self' https://challenges.cloudflare.com;
  frame-src 'self' https://challenges.cloudflare.com;
">

Common Patterns

Pattern 1: Hono + Cloudflare Workers

import { Hono } from 'hono'

type Bindings = {
  TURNSTILE_SECRET_KEY: string
  TURNSTILE_SITE_KEY: string
}

const app = new Hono<{ Bindings: Bindings }>()

app.post('/api/login', async (c) => {
  const body = await c.req.formData()
  const token = body.get('cf-turnstile-response')

  if (!token) {
    return c.text('Missing Turnstile token', 400)
  }

  // Validate token
  const verifyFormData = new FormData()
  verifyFormData.append('secret', c.env.TURNSTILE_SECRET_KEY)
  verifyFormData.append('response', token.toString())
  verifyFormData.append('remoteip', c.req.header('CF-Connecting-IP') || '')

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

  const outcome = await verifyResult.json<{ success: boolean }>()

  if (!outcome.success) {
    return c.text('Invalid Turnstile token', 401)
  }

  // Process login
  return c.json({ message: 'Login successful' })
})

export default app

When to use: API routes in Cloudflare Workers with Hono framework

Pattern 2: React + Next.js App Router

'use client'

import { Turnstile } from '@marsidev/react-turnstile'
import { useState } from 'react'

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

  async function handleSubmit(e: React.FormEvent<HTMLFormElement>) {
    e.preventDefault()

    if (!token) {
      setError('Please complete the challenge')
      return
    }

    const formData = new FormData(e.currentTarget)
    formData.append('cf-turnstile-response', token)

    const response = await fetch('/api/contact', {
      method: 'POST',
      body: formData,
    })

    if (!response.ok) {
      setError('Submission failed')
      return
    }

    // Success
  }

  return (
    <form onSubmit={handleSubmit}>
      <input name="email" type="email" required />
      <textarea name="message" required />

      <Turnstile
        siteKey={process.env.NEXT_PUBLIC_TURNSTILE_SITE_KEY!}
        onSuccess={setToken}
        onError={() => setError('Challenge failed')}
        onExpire={() => setToken(undefined)}
      />

      {error && <div className="error">{error}</div>}

      <button type="submit" disabled={!token}>
        Submit
      </button>
    </form>
  )
}

When to use: Client-side forms in Next.js with React hooks

Testing Keys

Dummy Sitekeys (client):

Always pass: 1x00000000000000000000AA
Always block: 2x00000000000000000000AB
Force interactive: 3x00000000000000000000FF

Dummy Secret Keys (server):

Always pass: 1x0000000000000000000000000000000AA
Always fail: 2x0000000000000000000000000000000AA
Token already spent: 3x0000000000000000000000000000000AA

Bundled Resources

Scripts: check-csp.sh - Verify CSP allows Turnstile

References:

widget-configs.md - All configuration options
error-codes.md - Error code troubleshooting (100*/200*/300*/400*/600*)
testing-guide.md - Testing strategies, dummy keys
react-integration.md - React/Next.js patterns

Templates: Complete examples for Hono, React, implicit/explicit rendering, validation

Advanced Features

Pre-Clearance (SPAs): Issue cookie that persists across page navigations

turnstile.render('#container', {
  sitekey: SITE_KEY,
  callback: async (token) => {
    await fetch('/api/pre-clearance', { method: 'POST', body: JSON.stringify({ token }) })
  }
})

Custom Actions & Data: Track challenge types, pass custom data (max 255 chars)

turnstile.render('#container', {
  action: 'login',  // Track in analytics
  cdata: JSON.stringify({ userId: '123' }),  // Custom payload
})

Error Handling: Use retry: 'auto' and error-callback for resilience

turnstile.render('#container', {
  retry: 'auto',
  'retry-interval': 8000,  // ms between retries
  'error-callback': (error) => { /* handle or show fallback */ }
})

Dependencies

Required: None (loads from CDN) React: @marsidev/react-turnstile@1.3.1 (Cloudflare-recommended), turnstile-types@1.2.3 Other: vue-turnstile, ngx-turnstile, svelte-turnstile, @nuxtjs/turnstile

Official Documentation

https://developers.cloudflare.com/turnstile/
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:

Check token hasn't expired (5 min TTL)
Verify secret key is correct
Ensure token hasn't been validated before (single-use)
Check hostname matches widget configuration

Problem: CSP blocking iframe (Error 200500)

Solution: Add CSP directives:

<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:

// jest.setup.ts
jest.mock('@marsidev/react-turnstile', () => ({
  Turnstile: () => <div data-testid="turnstile-mock" />,
}))

Errors Prevented: 12 documented issues (Safari 18 Hide IP, Brave confetti, Next.js Jest, CSP blocking, token reuse, expiration, hostname allowlist, widget crash 300030, config error 600010, missing validation, GET request, secret exposure)

cloudflare-turnstile