You set up a residential proxy, ran your scraper, and for two days everything worked. Then the blocks started. Status 403. CAPTCHAs. Empty responses. You check your proxy dashboard—IPs are online, traffic looks normal. What went wrong?
The answer is usually not your proxy provider. It’s detection. Many “residential” IPs leak data that tells websites you’re not a real user. The fix isn’t buying more IPs. It’s running a detection check before you start scraping.
Why Detection Matters More Than Speed
Beginners obsess over proxy speed. Experienced operators obsess over detection. A fast proxy that gets blocked is useless. A slower proxy that passes as a real residential user is gold.
Websites use three main detection methods:
- IP reputation – Is the IP known as a proxy or datacenter IP?
- Behavioral analysis – Are your requests too fast or too regular?
- Leak checks – Does your browser or tool reveal your real IP, DNS, or WebRTC info?
A good residential proxy passes all three. A bad one passes none.
Step-by-Step Detection Checklist
Use this checklist to test any residential proxy before you run a real job.
1. Check for IP Leaks
Open a browser with the proxy configured. Go to ipleak.net. If you see your real IP anywhere, your proxy is leaking. That’s an instant fail.
What to look for: Your real IP should not appear in the IP Address, DNS Addresses, or WebRTC Detection sections.
2. Verify the IP Type
Not all “residential” IPs are residential. Some providers mix in datacenter IPs. Use whatismyipaddress.com to check the ISP. If it shows a hosting company like DigitalOcean, AWS, or Hetzner, that IP is datacenter, not residential.
Pass condition: The ISP should be a real ISP like Comcast, AT&T, Deutsche Telekom, or similar.
3. Test DNS Leaks
Some proxies route your traffic but let DNS requests go through your real connection. Use dnsleaktest.com. Run the extended test. All DNS servers should be in the same country as your proxy IP.
Fail sign: DNS servers from your home country or ISP appear.
4. Check WebRTC Leaks
WebRTC can expose your real IP even when using a proxy. In Chrome, install a WebRTC leak blocker or use browserleaks.com/webrtc. If your real IP shows up, websites can see it.
Fix: Disable WebRTC in your browser or use a tool that blocks it.
5. Run a Real-World Request
Don’t rely on generic checkers. Send a request to the website you plan to scrape. Look for:
- HTTP status 200 – Good.
- CAPTCHA or challenge page – Bad. Your proxy is flagged.
- Redirect to a login page – Bad. The site suspects bot behavior.
Pro tip: Check the response body for phrases like “please verify you are human” or “access denied.”
Common Mistakes Beginners Make
- Only checking IP location – A residential IP from the right country can still be flagged if it has a bad reputation.
- Ignoring DNS leaks – Many proxy setups hide the IP but leak DNS. Websites detect this.
- Testing with a browser, then scraping with code – Browser behavior differs from HTTP clients like
requestsin Python. Always test with the same tool you’ll use for scraping. - Assuming all residential proxies are equal – Some providers recycle IPs heavily. A “fresh” IP might already be blocked on Amazon or eBay.
Mini Example: The Price Checker That Failed Until We Checked for Leaks
A team was scraping competitor prices daily. Every morning, the first 50 requests worked. Then blocks started. They bought more IPs, but the pattern repeated.
We ran the detection checklist. The proxy passed IP type and DNS checks. But WebRTC leaks showed their real IP. Every browser-based request leaked their home IP to the target website.
Fix: They switched to a headless browser with WebRTC disabled. Blocks dropped by 90%. No new IPs needed.
