Browser Console CAPTCHA Detection: Finding Sitekeys and Parameters

Before you can solve a CAPTCHA with CaptchaAI, you need to know what type of CAPTCHA the page uses and extract the right parameters (sitekey, action, s value, etc.). The browser console is the fastest way to find all of this.

Identifying the CAPTCHA type

Open DevTools (F12) and run this snippet in the Console tab:

(function detectCaptcha() {
  const results = [];

  // reCAPTCHA v2 / v2 Invisible
  const recaptchaWidgets = document.querySelectorAll('.g-recaptcha');
  recaptchaWidgets.forEach((el, i) => {
    results.push({
      type: 'reCAPTCHA v2',
      sitekey: el.getAttribute('data-sitekey'),
      size: el.getAttribute('data-size') || 'normal',
      callback: el.getAttribute('data-callback') || 'none'
    });
  });

  // reCAPTCHA v3 (loaded via script)
  const recaptchaScripts = document.querySelectorAll(
    'script[src*="recaptcha/api.js"], script[src*="recaptcha/enterprise.js"]'
  );
  recaptchaScripts.forEach(script => {
    const renderMatch = script.src.match(/render=([A-Za-z0-9_-]+)/);
    if (renderMatch && renderMatch[1] !== 'explicit') {
      results.push({
        type: 'reCAPTCHA v3',
        sitekey: renderMatch[1],
        enterprise: script.src.includes('enterprise')
      });
    }
  });

  // Cloudflare Turnstile
  const turnstileWidgets = document.querySelectorAll('.cf-turnstile');
  turnstileWidgets.forEach(el => {
    results.push({
      type: 'Cloudflare Turnstile',
      sitekey: el.getAttribute('data-sitekey'),
      action: el.getAttribute('data-action') || 'none'
    });
  });

  // GeeTest
  if (typeof initGeetest !== 'undefined' || document.querySelector('.geetest_holder')) {
    results.push({
      type: 'GeeTest',
      note: 'Check network tab for gt and challenge parameters'
    });
  }

  // hCaptcha
  const hcaptchaWidgets = document.querySelectorAll('.h-captcha');
  hcaptchaWidgets.forEach(el => {
    results.push({
      type: 'hCaptcha',
      sitekey: el.getAttribute('data-sitekey')
    });
  });

  if (results.length === 0) {
    console.log('No CAPTCHA widgets detected in the DOM.');
    console.log('Check: iframes, lazy-loaded scripts, or network requests.');
  } else {
    console.table(results);
  }

  return results;
})();

Expected output (example):

┌─────────┬──────────────┬──────────────────────┬──────────┐
│ (index) │     type     │       sitekey        │   size   │
├─────────┼──────────────┼──────────────────────┼──────────┤
│    0    │ 'reCAPTCHA v2' │ '6Le-SITEKEY-abc' │ 'normal' │
└─────────┴──────────────┴──────────────────────┴──────────┘

Extracting reCAPTCHA v2 parameters

What CaptchaAI needs:

Console command:

document.querySelectorAll('.g-recaptcha').forEach((el, i) => {
  console.log(`Widget ${i}:`, {
    sitekey: el.getAttribute('data-sitekey'),
    size: el.getAttribute('data-size'),
    callback: el.getAttribute('data-callback'),
    's_value': el.getAttribute('data-s'),
    pageurl: window.location.href
  });
});

Extracting reCAPTCHA v3 parameters

reCAPTCHA v3 has no visible widget. Find the sitekey from the script tag or by intercepting grecaptcha.execute:

// Method 1: Script tag
document.querySelectorAll('script[src*="recaptcha"]').forEach(s => {
  const match = s.src.match(/render=([A-Za-z0-9_-]+)/);
  if (match) console.log('v3 sitekey:', match[1]);
});

// Method 2: Intercept execute calls (run BEFORE page load in DevTools Sources)
const origExecute = grecaptcha.execute;
grecaptcha.execute = function(sitekey, opts) {
  console.log('v3 execute intercepted:', { sitekey, action: opts?.action });
  return origExecute.apply(this, arguments);
};

What CaptchaAI needs for v3: googlekey, pageurl, action (from opts.action), and min_score (optional).

Extracting Cloudflare Turnstile parameters

document.querySelectorAll('.cf-turnstile').forEach((el, i) => {
  console.log(`Turnstile ${i}:`, {
    sitekey: el.getAttribute('data-sitekey'),
    action: el.getAttribute('data-action'),
    cData: el.getAttribute('data-cdata'),
    pageurl: window.location.href
  });
});

If the widget is rendered via JavaScript (no .cf-turnstile div), search the page source:

// Search all script contents for turnstile.render calls
document.querySelectorAll('script:not([src])').forEach(s => {
  if (s.textContent.includes('turnstile.render')) {
    const match = s.textContent.match(/sitekey\s*:\s*['"]([^'"]+)['"]/);
    if (match) console.log('Turnstile sitekey:', match[1]);
  }
});

Extracting GeeTest parameters

GeeTest requires gt, challenge, and optionally api_server. These come from a network request, not the DOM.

1. Open the Network tab in DevTools
2. Filter by register or captcha
3. Find the JSON response containing gt and challenge

// Quick check for GeeTest on the page
if (document.querySelector('.geetest_holder')) {
  console.log('GeeTest detected. Check Network tab for:');
  console.log('  - gt (32-char hex string)');
  console.log('  - challenge (32-char hex string)');
  console.log('  - api_server (optional, e.g. api.geetest.com)');
}

Extracting sitekeys from iframes

When the CAPTCHA is inside an iframe, check the iframe's src:

document.querySelectorAll('iframe').forEach((iframe, i) => {
  const src = iframe.src || '';
  if (src.includes('recaptcha')) {
    const match = src.match(/k=([A-Za-z0-9_-]+)/);
    console.log(`iframe ${i} — reCAPTCHA sitekey:`, match?.[1]);
  }
  if (src.includes('turnstile') || src.includes('challenges.cloudflare')) {
    console.log(`iframe ${i} — Cloudflare challenge:`, src);
  }
});

Checking for lazy-loaded CAPTCHAs

Some CAPTCHAs load only after user interaction (button click, scroll). Use a MutationObserver to catch them:

const observer = new MutationObserver(mutations => {
  for (const mutation of mutations) {
    for (const node of mutation.addedNodes) {
      if (node.nodeType !== 1) continue;
      if (node.matches?.('.g-recaptcha, .cf-turnstile, .h-captcha')) {
        console.log('CAPTCHA widget added:', node.className,
          node.getAttribute('data-sitekey'));
      }
      if (node.tagName === 'IFRAME' && node.src?.includes('recaptcha')) {
        console.log('reCAPTCHA iframe added:', node.src);
      }
    }
  }
});

observer.observe(document.body, { childList: true, subtree: true });
console.log('Watching for dynamically loaded CAPTCHAs...');

Troubleshooting

FAQ

Can I extract parameters without opening the browser?

You can fetch the page source with curl or requests and search for sitekeys with regex. But JavaScript-rendered CAPTCHAs require a real browser or headless browser to detect.

What if the page uses reCAPTCHA Enterprise?

Enterprise uses the same sitekey extraction methods. The script URL will contain enterprise.js instead of api.js. Pass the enterprise flag when submitting to CaptchaAI.

Use the parameters you find to solve CAPTCHAs with CaptchaAI

Get your API key at captchaai.com.

Related guides

• Extracting reCAPTCHA Parameters from Page Source
• Iframe CAPTCHA Extraction: Nested Frames
• Handling Multiple CAPTCHAs on a Single Page