CapMonster CAPTCHA Solver

Solve CAPTCHAs (reCAPTCHA v2/v3, hCaptcha, Cloudflare Turnstile, image CAPTCHAs) using CapMonster Cloud API. Use when browser automation encounters CAPTCHA challenges.

CapMonster Cloud CAPTCHA Solver

Solve CAPTCHAs programmatically via CapMonster Cloud API during browser automation.

API Info

• Base URL: https://api.capmonster.cloud
• API Key: ${CAPMONSTER_API_KEY}
• Docs: https://docs.capmonster.cloud/
• Python Client: tools/capmonster-cloud/capmonster_api.py

Pricing (per 1000 solves)

Type	Price	Avg Time
reCAPTCHA v2	$0.60	10-30s
reCAPTCHA v3	$0.90	5-15s
hCaptcha	$1.50	10-30s
Cloudflare Turnstile	$1.20	5-15s
Image CAPTCHA	$0.04	2-5s

Quick Reference

Check Balance

bash

curl -s -X POST https://api.capmonster.cloud/getBalance \
  -H "Content-Type: application/json" \
  -d '{"clientKey": "${CAPMONSTER_API_KEY}"}' | jq .balance

Using Python Client

python

import sys
sys.path.insert(0, '/Users/eason/clawd/tools/capmonster-cloud')
from capmonster_api import CapMonsterClient

client = CapMonsterClient("${CAPMONSTER_API_KEY}")

# Check balance
print(f"Balance: ${client.get_balance()}")

# Solve reCAPTCHA v2
token = client.solve_recaptcha_v2(
    website_url="https://example.com/page-with-captcha",
    website_key="6Le-wvkSAAAAAPBMRTvw0Q4Muexq9bi0DJwx_mJ-"
)

---

Complete Workflow: Browser Automation + CAPTCHA Solving

Step 1: Detect CAPTCHA on Page

Take a browser snapshot and check for CAPTCHA indicators:

javascript

// Via browser action=act evaluate
browser action=act profile=chrome request={
  "kind": "evaluate",
  "fn": "(() => {
    const indicators = {
      recaptchaV2: !!document.querySelector('.g-recaptcha, [data-sitekey], iframe[src*=\"recaptcha\"]'),
      recaptchaV3: !!document.querySelector('script[src*=\"recaptcha/api.js?render=\"]'),
      hcaptcha: !!document.querySelector('.h-captcha, [data-hcaptcha-sitekey], iframe[src*=\"hcaptcha\"]'),
      turnstile: !!document.querySelector('.cf-turnstile, [data-sitekey], iframe[src*=\"turnstile\"]')
    };
    return JSON.stringify(indicators);
  })()"
}

Step 2: Extract Site Key

reCAPTCHA v2:

javascript

// Option A: From data-sitekey attribute
document.querySelector('[data-sitekey]')?.dataset.sitekey

// Option B: From iframe src
document.querySelector('iframe[src*="recaptcha"]')?.src.match(/k=([^&]+)/)?.[1]

// Option C: From grecaptcha object
window.___grecaptcha_cfg?.clients?.[0]?.Y?.Y?.sitekey

reCAPTCHA v3:

javascript

// From script src
document.querySelector('script[src*="recaptcha/api.js?render="]')?.src.match(/render=([^&]+)/)?.[1]

// Or from grecaptcha config
window.___grecaptcha_cfg?.clients?.[0]?.Y?.Y?.sitekey

hCaptcha:

javascript

document.querySelector('[data-hcaptcha-sitekey], .h-captcha[data-sitekey]')?.dataset.sitekey ||
document.querySelector('[data-hcaptcha-sitekey]')?.getAttribute('data-hcaptcha-sitekey')

Cloudflare Turnstile:

javascript

document.querySelector('.cf-turnstile[data-sitekey], [data-turnstile-sitekey]')?.dataset.sitekey

Step 3: Submit to CapMonster API

Using curl (shell):

bash

# Create task
TASK_ID=$(curl -s -X POST https://api.capmonster.cloud/createTask \
  -H "Content-Type: application/json" \
  -d '{
    "clientKey": "${CAPMONSTER_API_KEY}",
    "task": {
      "type": "RecaptchaV2TaskProxyless",
      "websiteURL": "https://scholar.google.com/",
      "websiteKey": "SITEKEY_HERE"
    }
  }' | jq -r .taskId)

echo "Task ID: $TASK_ID"

Using Python:

python

import sys
sys.path.insert(0, '/Users/eason/clawd/tools/capmonster-cloud')
from capmonster_api import CapMonsterClient

client = CapMonsterClient("${CAPMONSTER_API_KEY}")

# For reCAPTCHA v2
token = client.solve_recaptcha_v2(
    website_url="https://scholar.google.com/",
    website_key="EXTRACTED_SITEKEY"
)

# For reCAPTCHA v3
token = client.solve_recaptcha_v3(
    website_url="https://example.com/",
    website_key="EXTRACTED_SITEKEY",
    min_score=0.7,
    page_action="submit"  # Check page source for action name
)

# For hCaptcha
token = client.solve_hcaptcha(
    website_url="https://example.com/",
    website_key="EXTRACTED_SITEKEY"
)

# For Turnstile
token = client.solve_turnstile(
    website_url="https://example.com/",
    website_key="EXTRACTED_SITEKEY"
)

Step 4: Poll for Solution

Using curl:

bash

# Poll until ready (max 120 seconds)
for i in {1..60}; do
  RESULT=$(curl -s -X POST https://api.capmonster.cloud/getTaskResult \
    -H "Content-Type: application/json" \
    -d "{\"clientKey\": \"${CAPMONSTER_API_KEY}\", \"taskId\": $TASK_ID}")
  
  STATUS=$(echo "$RESULT" | jq -r .status)
  
  if [ "$STATUS" = "ready" ]; then
    TOKEN=$(echo "$RESULT" | jq -r '.solution.gRecaptchaResponse // .solution.token')
    echo "Token: $TOKEN"
    break
  fi
  
  echo "Status: $STATUS, waiting..."
  sleep 2
done

The Python client handles polling automatically with solve_and_wait().

Step 5: Inject Solution into Page

reCAPTCHA v2/v3:

javascript

// Via browser evaluate
browser action=act profile=chrome request={
  "kind": "evaluate",
  "fn": "(() => {
    const token = 'CAPMONSTER_TOKEN_HERE';
    
    // Method 1: Set textarea value (most common)
    const textarea = document.querySelector('#g-recaptcha-response, [name=\"g-recaptcha-response\"]');
    if (textarea) {
      textarea.value = token;
      textarea.style.display = 'block';  // Some sites hide it
    }
    
    // Method 2: Also set any iframe response
    document.querySelectorAll('iframe[src*=\"recaptcha\"]').forEach(iframe => {
      try {
        const doc = iframe.contentDocument || iframe.contentWindow.document;
        const ta = doc.querySelector('#g-recaptcha-response');
        if (ta) ta.value = token;
      } catch(e) {}
    });
    
    // Method 3: Trigger callback if exists
    if (typeof ___grecaptcha_cfg !== 'undefined') {
      const clients = ___grecaptcha_cfg.clients;
      for (let cid in clients) {
        const client = clients[cid];
        // Find callback
        const callback = client?.Y?.Y?.callback || client?.Y?.callback;
        if (typeof callback === 'function') {
          callback(token);
        }
      }
    }
    
    return 'Token injected';
  })()"
}

hCaptcha:

javascript

browser action=act profile=chrome request={
  "kind": "evaluate",
  "fn": "(() => {
    const token = 'CAPMONSTER_TOKEN_HERE';
    
    // Set response textarea
    const textarea = document.querySelector('[name=\"h-captcha-response\"], [name=\"g-recaptcha-response\"]');
    if (textarea) textarea.value = token;
    
    // Trigger callback
    if (typeof hcaptcha !== 'undefined') {
      // Find widget ID
      const widget = document.querySelector('.h-captcha');
      const widgetId = widget?.dataset.hcaptchaWidgetId || 0;
      // Some sites have custom callbacks
    }
    
    return 'hCaptcha token injected';
  })()"
}

Cloudflare Turnstile:

javascript

browser action=act profile=chrome request={
  "kind": "evaluate",
  "fn": "(() => {
    const token = 'CAPMONSTER_TOKEN_HERE';
    
    // Set the hidden input
    const input = document.querySelector('[name=\"cf-turnstile-response\"]');
    if (input) input.value = token;
    
    // Also set any callback data attribute
    const container = document.querySelector('.cf-turnstile');
    if (container && container.dataset.callback) {
      const callbackName = container.dataset.callback;
      if (typeof window[callbackName] === 'function') {
        window[callbackName](token);
      }
    }
    
    return 'Turnstile token injected';
  })()"
}

Step 6: Submit the Form

After injecting the token, submit the form:

javascript

// Click submit button
browser action=act profile=chrome request={"kind":"click","ref":"submit button ref"}

// Or trigger form submission
browser action=act profile=chrome request={
  "kind": "evaluate",
  "fn": "document.querySelector('form').submit()"
}

---

Google Scholar Specific

Google Scholar uses invisible reCAPTCHA v2 that triggers on suspicious activity.

Detection

javascript

// Check if blocked
const isBlocked = document.body.textContent.includes('unusual traffic') ||
                  document.body.textContent.includes('我們的系統') ||
                  !!document.querySelector('iframe[src*="recaptcha"]');

Extract Site Key

javascript

// Scholar's recaptcha iframe
const iframe = document.querySelector('iframe[src*="recaptcha"]');
const sitekey = iframe?.src.match(/k=([^&]+)/)?.[1];
// Usually: 6LfwuyUTAAAAAOAmoS0fdqijC2PbbdH4kjq62Y1b

Solve and Submit

python

import sys
sys.path.insert(0, '/Users/eason/clawd/tools/capmonster-cloud')
from capmonster_api import CapMonsterClient

client = CapMonsterClient("${CAPMONSTER_API_KEY}")

# Scholar's known sitekey (may change)
token = client.solve_recaptcha_v2(
    website_url="https://scholar.google.com/scholar?q=test",
    website_key="6LfwuyUTAAAAAOAmoS0fdqijC2PbbdH4kjq62Y1b"
)

print(f"Token: {token[:50]}...")

Then inject via browser automation.

---

Image CAPTCHA

For traditional image CAPTCHAs (text recognition):

python

import base64
import sys
sys.path.insert(0, '/Users/eason/clawd/tools/capmonster-cloud')
from capmonster_api import CapMonsterClient

client = CapMonsterClient("${CAPMONSTER_API_KEY}")

# From file
text = client.solve_image_captcha(image_path="/tmp/captcha.png")

# From base64
with open("/tmp/captcha.png", "rb") as f:
    b64 = base64.b64encode(f.read()).decode()
text = client.solve_image_captcha(image_base64=b64)

print(f"CAPTCHA text: {text}")

---

All-in-One Shell Script

Save as solve-recaptcha.sh:

bash

#!/bin/bash
# Usage: ./solve-recaptcha.sh <website_url> <sitekey>

API_KEY="${CAPMONSTER_API_KEY}"
WEBSITE_URL="$1"
SITEKEY="$2"

# Create task
echo "Creating task..."
RESPONSE=$(curl -s -X POST https://api.capmonster.cloud/createTask \
  -H "Content-Type: application/json" \
  -d "{
    \"clientKey\": \"$API_KEY\",
    \"task\": {
      \"type\": \"RecaptchaV2TaskProxyless\",
      \"websiteURL\": \"$WEBSITE_URL\",
      \"websiteKey\": \"$SITEKEY\"
    }
  }")

TASK_ID=$(echo "$RESPONSE" | jq -r .taskId)
ERROR_ID=$(echo "$RESPONSE" | jq -r .errorId)

if [ "$ERROR_ID" != "0" ]; then
  echo "Error: $(echo "$RESPONSE" | jq -r .errorDescription)"
  exit 1
fi

echo "Task ID: $TASK_ID"

# Poll for result
echo "Waiting for solution..."
for i in {1..60}; do
  RESULT=$(curl -s -X POST https://api.capmonster.cloud/getTaskResult \
    -H "Content-Type: application/json" \
    -d "{\"clientKey\": \"$API_KEY\", \"taskId\": $TASK_ID}")
  
  STATUS=$(echo "$RESULT" | jq -r .status)
  
  if [ "$STATUS" = "ready" ]; then
    TOKEN=$(echo "$RESULT" | jq -r '.solution.gRecaptchaResponse')
    COST=$(echo "$RESULT" | jq -r '.cost')
    echo "✅ Solved! Cost: \$$COST"
    echo ""
    echo "TOKEN:"
    echo "$TOKEN"
    exit 0
  fi
  
  printf "."
  sleep 2
done

echo ""
echo "❌ Timeout after 120 seconds"
exit 1

---

Troubleshooting

Token Invalid / Expired

• Tokens expire in ~2 minutes
• Inject and submit immediately after receiving
• Make sure websiteURL matches the actual page URL

ERROR_CAPTCHA_UNSOLVABLE

• Retry 2-3 times
• Check if sitekey is correct
• Page may have additional protections

ERROR_RECAPTCHA_TIMEOUT

• Network issue between CapMonster and target
• Try again, or use proxy version (RecaptchaV2Task)

Token Injected but Form Fails

• Site may validate token server-side with IP check
• Try using proxy version with your IP
• Some sites need callback to be triggered

Finding the Callback

javascript

// Check grecaptcha config for callback
JSON.stringify(___grecaptcha_cfg, (k, v) => typeof v === 'function' ? '[Function]' : v, 2)

// Or check data-callback attribute
document.querySelector('[data-callback]')?.dataset.callback

---

Best Practices

1. Extract sitekey fresh - Don't hardcode, sites may rotate
2. Use correct URL - Must match the page showing CAPTCHA
3. Inject quickly - Tokens expire in ~120 seconds
4. Check for v3 - Some sites use v3 (invisible), need pageAction
5. Monitor balance - Set up low-balance alerts
6. Retry on failure - CapMonster may fail occasionally

Cost Estimation

Use Case	CAPTCHAs/day	Monthly Cost
Light (research)	10	~$0.18
Medium (scraping)	100	~$1.80
Heavy (automation)	1000	~$18.00

Current balance is ~$10, good for ~16,000 reCAPTCHA v2 solves.