Your Scraper Has a Bad Fake ID (And That's Why It Gets Blocked)

So I was trying to scrape Stack Overflow for every question tagged proxies. I wanted to see what problems people get stuck on the most. Seemed simple enough.

I set up my residential proxies, rotated my user agents, and fired up my Python script.

It got blocked almost instantly.

Here's what I wish someone had told me from the start: all that stuff about rotating IPs is only half the story. It’s like trying to get into a high-tech club by changing your t-shirt every five minutes. The bouncer doesn't care about your shirt; they're scanning your ID.

And your scraper has a really, really bad fake ID.

The Real Reason You Get Blocked

Every time your script connects to a website over HTTPS, it does a "handshake" to set up a secure connection. The way it performs this handshake—the specific combination of crypto stuff it offers—creates a unique signature. It's called a TLS fingerprint (or a JA3 fingerprint, if you want to get technical).

And the default fingerprint for Python's requests library is famous. It's so obviously a script that anti-bot systems like Cloudflare can spot it from a mile away.

It's the digital equivalent of showing up with a fake ID where the hologram is just a piece of tinfoil. It doesn't matter what name or address is on it (your IP and user-agent). It's an instant dead giveaway.

Code That Screams "I'm a Bot"

This is probably what your code looks like. It's what mine looked like. And it’s the reason it fails.

# The code that gets you blocked.
import requests

# This request has a default Python TLS fingerprint.
# It's an instant "Access Denied" on any protected site.
# No amount of proxies or headers will fix this.
try:
    response = requests.get("https://stackoverflow.com/questions/tagged/proxies")
    print(f"Status: {response.status_code}") # This will lie to you with a 200...
    print("Does 's-post-summary' exist?", 's-post-summary' in response.text) # ...but the real content is missing.
except Exception as e:
    print(f"Failed: {e}")

On a site like Stack Overflow, you might not get an outright 403 Forbidden error. Instead, you'll get a page with a CAPTCHA or a "please verify you are human" message. The data you actually want is nowhere to be found.

Code That Actually Works

The fix is to stop using an ID made of cardboard and tinfoil. You need one that looks legit.

We use a library called tls-client for this. It's designed to perfectly copy the TLS fingerprint of real web browsers, so your scraper's handshake looks exactly like one from a normal Chrome or Firefox user.

# The code that doesn't suck.
import tls_client

# We're creating a session that has the fingerprint
# of a real Chrome browser.
session = tls_client.Session(
    client_identifier="chrome_117",
    random_tls_extension_order=True
)

# This request looks 100% human to the server.
response = session.get("https://stackoverflow.com/questions/tagged/proxies")

print(f"Status: {response.status_code}") # A real 200 OK.
print("Does 's-post-summary' exist?", 's-post-summary' in response.text) # True. The data is actually there.

That’s it. By swapping out one library, we fixed the single biggest giveaway. We gave our scraper a legit ID.

The Bottom Line

Stop obsessing over complicated IP rotation schemes and "warming up" sessions. You're trying to solve the wrong problem. If your scraper's fundamental signature is robotic, nothing else matters.

Get your fingerprint right first. Make your script's handshake look human.

It’s not about having a perfect disguise. It’s about not showing up with a fake ID that was obviously printed on a home computer. Once you fix that, web scraping starts to actually work.