How to Detect Google AdSense on a Website with Python

Detecting whether a website is running Google AdSense is a common task for digital marketers, SEO researchers, and competitive analysts. From a technical perspective, AdSense works by injecting a specific JavaScript library into the page, usually accompanied by a unique "Publisher ID" (formatted as pub-xxxxxxxxxxxxxxxx).

In Python, we can identify these markers by "scraping" the HTML and searching for the signature AdSense scripts.

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🕵️ How to Identify AdSense Markers

There are three primary "fingerprints" an AdSense-enabled site leaves behind:

1. The Script Tag: Looking for adsbygoogle.js or pagead2.googlesyndication.com.
2. The Publisher ID: Searching for the regex pattern pub-[0-9]+.
3. The ads.txt File: A public file located at domain.com/ads.txt that lists authorized digital sellers.

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💻 The Implementation

This script uses requests to fetch the page and BeautifulSoup to parse the HTML. I have also added a check for the ads.txt file, which is the most "official" way to verify AdSense.

# 🔍 Python Script: Google AdSense Detector

### 1. Requirements
```bash
pip install requests beautifulsoup4

2. The Code

import requests
from bs4 import BeautifulSoup
import re

def check_adsense(url):
    # Ensure the URL starts with http
    if not url.startswith('http'):
        url = 'https://' + url

    headers = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebkit/537.36'}

    try:
        # 1. Check the Homepage HTML
        response = requests.get(url, headers=headers, timeout=10)
        soup = BeautifulSoup(response.text, 'html.parser')
        html_content = response.text.lower()

        # Look for the AdSense script signatures
        signatures = [
            'googlesyndication.com',
            'adsbygoogle.js',
            'pagead2'
        ]

        has_script = any(sig in html_content for sig in signatures)

        # 2. Look for Publisher ID (pub-xxxxxxxx)
        pub_id_match = re.search(r'pub-\d+', html_content)
        pub_id = pub_id_match.group(0) if pub_id_match else "Not Found"

        # 3. Check for ads.txt (The most reliable indicator)
        domain = url.split("//")[-1].split("/")[0]
        ads_txt_url = f"https://{domain}/ads.txt"
        ads_txt_response = requests.get(ads_txt_url, headers=headers, timeout=5)

        has_ads_txt = "google.com, pub-" in ads_txt_response.text.lower() if ads_txt_response.status_code == 200 else False

        # --- Report Results ---
        print(f"📊 Results for: {url}")
        print(f"✅ AdSense Script Found: {has_script}")
        print(f"🆔 Publisher ID: {pub_id}")
        print(f"📄 Valid ads.txt Entry: {has_ads_txt}")

        if has_script or has_ads_txt:
            print("\n🚀 Verdict: This website is likely running AdSense.")
        else:
            print("\n📁 Verdict: No AdSense detected.")

    except Exception as e:
        print(f"❌ Error checking {url}: {e}")

# --- Test It ---
check_adsense("[https://www.example.com](https://www.example.com)")

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⚖️ Detection Methods Comparison

Method	Reliability	Why it works
HTML Script Scan	Medium	Quickest way, but can be blocked by certain "lazy loading" setups.
Regex Pub-ID Search	High	Almost all AdSense implementations require the pub- string to be present.
ads.txt Verification	Highest	This is a security standard. If Google is authorized to sell ads, it must be here.

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📚 Sources & Technical Refs

• [1.1] Google AdSense Help: How to find your Publisher ID - Understanding the ID format.
• [2.1] IAB Tech Lab: ads.txt Specification - The technical standard for the ads.txt file.
• [3.1] BeautifulSoup Docs: Searching the tree - Efficient ways to find tags and attributes.

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📋 Pro Tip: Handling Anti-Bot Protection

Many large sites use Cloudflare or other "WAF" (Web Application Firewalls) that block Python's default requests library. If you find your script getting a 403 Forbidden error, you may need to use Selenium or Playwright to simulate a real Chrome browser.