Cloudflare 403 & Turnstile Troubleshooting Checklist for Scraping Teams

[Outbound Scraper Request]
       |
       v
[Layer 3/4: IP Reputation & ASN Check] ---> (Residential Proxy Passes 100%)
       |
       v
[Layer 6/7: TLS JA3/JA4 Fingerprint Check] ---> (Standard Python/Node HTTP Clients FAIL Here!)
       |
       v
[Layer 7: HTTP/2 SETTINGS & Header Order]  ---> (Mismatched Pseudo-Headers FAIL Here!)
       |
       v
[Layer 7: JavaScript / Turnstile Challenge] ---> (Headless Browser / Captcha Solver Required)

import asyncio
from curl_cffi import requests as cffi_requests

# BytesFlows Residential Proxy Configuration
PROXY_HOST = "p1.bytesflows.com:8001"
BASE_USER = "your-sub-user"
PASSWORD = "your-password"

def fetch_cloudflare_protected_url(url: str, target_country: str = "us") -> dict:
    """
    Fetches a Cloudflare-protected URL by impersonating Chrome's TLS JA3/JA4 
    fingerprint and HTTP/2 pseudo-header structure over residential IPs.
    """
    # Configure geo-targeted residential proxy
    proxy_auth = f"http://{BASE_USER}-loc-{target_country}:{PASSWORD}@{PROXY_HOST}"
    proxies = {"http": proxy_auth, "https": proxy_auth}
    
    # Standard Chrome browser headers aligned with US localization
    headers = {
        "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8",
        "Accept-Language": "en-US,en;q=0.9",
        "Accept-Encoding": "gzip, deflate, br, zstd",
        "Sec-Ch-Ua": '"Chromium";v="126", "Google Chrome";v="126", "Not-A.Brand";v="24"',
        "Sec-Ch-Ua-Mobile": "?0",
        "Sec-Ch-Ua-Platform": '"Windows"',
        "Sec-Fetch-Dest": "document",
        "Sec-Fetch-Mode": "navigate",
        "Sec-Fetch-Site": "none",
        "Sec-Fetch-User": "?1",
        "Upgrade-Insecure-Requests": "1"
    }

    try:
        # 'impersonate="chrome124"' replicates exact TLS ciphers & HTTP/2 SETTINGS
        response = cffi_requests.get(
            url,
            headers=headers,
            proxies=proxies,
            impersonate="chrome124",
            timeout=15
        )
        
        return {
            "status_code": response.status_code,
            "url": url,
            "bytes_received": len(response.content),
            "cf_ray_header": response.headers.get("cf-ray", "N/A"),
            "server_header": response.headers.get("server", "N/A"),
            "html_preview": response.text[:300]
        }
    except Exception as e:
        return {"status": "error", "message": str(e

), "url": url}

if __name__ == "__main__":
    # Test against Cloudflare diagnostic and protected endpoints
    targets = [
        "https://tls.peeltech.ca/json",  # Inspects TLS fingerprint
        "https://httpbin.org/headers"
    ]
    
    for target in targets:
        result = fetch_cloudflare_protected_url(target, target_country="us")
        print(f"[{result.get('status_code', 'ERR')}] {target} | CF-Ray: {result.get('cf_ray_header')}")