Crawler keeps getting blocked by Cloudflare

If your crawler is getting blocked by Cloudflare, the safest and most reliable approach is to avoid bypassing protections and instead make the crawler behave like a legitimate, low-impact client.

Common causes

• Too many requests too quickly
• Missing or suspicious headers
• Repeated requests from the same IP / ASN
• No cookies / session persistence
• Headless-browser fingerprints
• Hitting pages that are protected by bot management or JS challenges

What you can do

1. Throttle aggressively

   • Add delays between requests
   • Limit concurrency
   • Use exponential backoff on 403/429/503 responses

2. Cache and deduplicate

   • Don’t refetch the same pages unnecessarily
   • Use ETags / If-Modified-Since when available

3. Use a proper user agent

   • Identify your crawler honestly
   • Include contact info if appropriate

4. Preserve sessions

   • Keep cookies
   • Reuse connections where possible

5. Respect robots.txt and site policies

   • If crawling is disallowed, don’t crawl those paths

6. Request permission / allowlisting

   • For sites you control or have a business relationship with, ask the owner to:
     • allowlist your IPs
     • create a WAF rule for your crawler
     • set up a bot management exception for specific routes

7. Use the site’s official API

   • Often the best solution if one exists

If you control the site

You can reduce false positives by:

• lowering Cloudflare bot sensitivity for your crawler’s IPs
• creating firewall rules for trusted user agents or IP ranges
• allowing specific paths or API endpoints
• reviewing logs to see what rule is triggering the block

What not to do

I can’t help with instructions for evading Cloudflare’s anti-bot protections or bypassing challenges.

If you want, I can help you with either of these:

• debugging your crawler behavior to reduce blocks
• setting up a Cloudflare allowlist/firewall rule for a crawler you control