How CMS Detection Actually Works: The Technical Breakdown (From Someone Who's Been Doing This for Years)

So you want to know how CMS detection actually works under the hood? Cool. Pull up a chair, grab some coffee, and let me show you. This is going to get a bit technical, but I promise I'll keep it interesting. And hey, if I can explain this to my non-technical friends (which I've done, many times, usually after a few beers), I can explain it to you.

First Things First: What Are We Even Looking For?

Here's the thing about websites – they're basically just files sitting on a server somewhere. HTML, CSS, JavaScript, images, maybe some PHP or Python running in the background. Every CMS leaves fingerprints in these files. Not intentionally, usually. It's just how they're built.

Think of it like detective work. Except instead of looking for actual fingerprints, we're looking for things like specific file paths, certain JavaScript libraries, particular HTML patterns, or telltale HTTP headers. Each CMS has its own signature.

I remember when I first started doing this, I thought it would be super complicated. Turned out, most websites practically announce what CMS they're using. It's like someone wearing a band t-shirt – you don't need to ask what music they like.

The Five Main Detection Methods

Over the years, I've narrowed this down to five primary techniques. You can usually figure out any CMS using one or more of these methods. Let's break them down.

Method 1: Meta Tag Analysis (The Obvious One)

This is the easiest method, and honestly, it works way more often than you'd think. A lot of CMS platforms include a meta tag in the HTML that basically says "Hey, I'm WordPress!" or "Built with Joomla!"

Look at the source code of any page and search for something like this:

Boom. That's WordPress. Case closed. And it even tells you the version number. How nice of them.

Why do CMSs do this? A few reasons:
1. Brand awareness (free advertising)
2. Debugging (helps developers troubleshoot)
3. Community pride (some people are proud of their platform choice)
4. Nobody bothered to remove it

Now, here's where it gets interesting. A lot of security-conscious site owners remove this tag. They're thinking, "Why tell potential attackers exactly what CMS and version we're running?" And they're not wrong.

But here's the funny part – removing the generator tag doesn't really hide your CMS. It's like taking the license plate off your car. Sure, it's slightly harder to identify, but the car is still obviously a Honda Civic, you know?

I had a client once who was super proud that they'd "hidden" their WordPress site by removing the generator tag. Then I showed them about fifteen other ways to detect it. They were not amused.

Method 2: HTTP Headers (The Chatty Server)

Every time you visit a website, your browser and the server have a little conversation. The server sends back headers – basically metadata about the response. And sometimes, servers are really chatty.

You can check these headers in your browser's Developer Tools (F12, go to Network tab, reload the page, click on the first request, look at Headers). Or use cURL from the command line:

curl -I https://example.com

Common giveaway headers include:

X-Powered-By

X-Powered-By: PHP/8.1.0

Okay, so it's PHP-based. That narrows it down. Could be WordPress, Joomla, Drupal, or a bunch of others.

X-Generator

X-Generator: Drupal 9 (https://www.drupal.org)

Well, that's pretty explicit. Thanks, Drupal.

Server

Server: Apache/2.4.41

This tells us the web server software, which is less useful but can give hints.

Custom Headers

Some platforms add their own custom headers:

X-Shopify-Stage: production
X-Wix-Renderer-Server: app-jvm-12-123.45

It's like they're wearing name tags.

The thing about headers is they're often overlooked. People obsess over removing the generator meta tag from the HTML but forget the server is broadcasting the same information in the headers. Classic oversight.

Method 3: File Path and Directory Structure (The Fingerprint)

This is my favorite method because it's really hard to hide. Every CMS has certain files and directories that are pretty much always there. It's like looking for the engine in a car – it's always in roughly the same place.

WordPress has:
- /wp-content/ (themes, plugins, uploads)
- /wp-includes/ (core files)
- /wp-admin/ (admin area)
- wp-login.php (login page)

Joomla has:
- /components/
- /modules/
- /templates/
- /administrator/

Drupal has:
- /sites/
- /core/
- /modules/
- /themes/

Here's how I check this: I just try to access common paths. Open your browser and try:

https://example.com/wp-admin/

If you get a login screen, congrats – it's WordPress. Even if they've removed all other signs, this usually gives it away.

The funny thing is, some people try to rename these directories to hide their CMS. Like changing /wp-content/ to /content/. And sure, that works for basic detection. But there are usually so many other fingerprints that it doesn't matter. Plus, renaming core directories often breaks things, so most people don't bother.

I once saw a site that had renamed /wp-content/ to /definitely-not-wordpress/. I laughed. It was definitely WordPress.

Method 4: JavaScript and CSS Pattern Matching (The Code Signature)

Different CMSs load different JavaScript libraries and CSS files. And they usually load them from specific paths with specific names.

For example, WordPress loads jQuery from:

/wp-includes/js/jquery/jquery.min.js

And WordPress has a distinct way of handling JavaScript – it uses something called "wp-enqueue-script" which leaves certain patterns in the HTML.

Shopify sites load Shopify-specific JavaScript:

https://cdn.shopify.com/s/files/1/...

See that "cdn.shopify.com"? Dead giveaway.

Wix sites have super long, generated URLs that look completely crazy:

https://static.wixstatic.com/sites/2b4e1b7e-8c3e-4d7a-9f3a-1e5c8b9d2f4a/...

Nobody else generates URLs like that. It's uniquely Wix.

Here's a cool trick: search the page source for common JavaScript libraries and note what path they're loaded from. The path often reveals the CMS.

I built a simple script once that just looks for these patterns. It's basically a big list of "if you see this file path, it's this CMS." Worked about 80% of the time. Not bad for something I wrote in an afternoon.

Method 5: Behavioral Analysis (The Advanced Stuff)

This is where it gets really interesting. Different CMSs behave differently. They have different admin URLs, different AJAX patterns, different ways of handling cookies, different response times.

Cookie Patterns

WordPress sets cookies with specific names:

wordpressloggedin_[hash]
wp-settings-{user_id}

Joomla uses:

{hash}joomlasession

You can check cookies in your browser's DevTools (Application/Storage → Cookies).

AJAX Endpoints

WordPress uses admin-ajax.php for AJAX requests. Even if someone's tried to hide everything else, if you see:

https://example.com/wp-admin/admin-ajax.php

That's WordPress. The admin-ajax.php file is used by countless plugins and themes, so it's almost always there on production sites.

REST API

Modern WordPress has a REST API at:

https://example.com/wp-json/

Even if the site has removed all other WordPress signatures, this endpoint often remains. And it returns JSON that literally includes:

{
  "name": "Site Name",
  "description": "Just another WordPress site",
  ...
}

"Just another WordPress site" is the default tagline, and a lot of people never change it. I find this hilarious.

Error Pages

This one's sneaky. Try to access a page that doesn't exist:

https://example.com/this-page-definitely-does-not-exist

Different CMSs have different default 404 error pages. WordPress has a very distinct look (if using a default theme). Shopify's 404 pages often mention Shopify. It's not foolproof, but it's another data point.

Combining Methods: The Real-World Approach

Here's the truth: I almost never rely on just one method. I use multiple techniques to confirm. It's like a doctor running multiple tests to confirm a diagnosis.

My typical workflow:
1. Quick check for generator meta tag (10 seconds)
2. Try /wp-admin/ or other common paths (10 seconds)
3. Check for distinctive file patterns in the HTML (30 seconds)
4. Look at HTTP headers if still unsure (30 seconds)
5. Check the REST API endpoint if applicable (30 seconds)

Total time: maybe 2 minutes for a thorough check. And I'm accurate about 95% of the time.

The other 5%? Those are usually custom-built sites, heavily modified CMSs, or headless setups where the CMS is completely hidden behind a JavaScript framework.

The Tricky Cases: When Detection Gets Hard

Not every site is easy to detect. Some are genuinely challenging.

Heavily Customized CMSs

I once analyzed a major news website. They were using WordPress, but so heavily customized that almost nothing looked like standard WordPress. Custom themes, custom plugins, renamed directories, removed meta tags, everything.

But they couldn't hide the AJAX patterns. I noticed requests going to admin-ajax.php. Found it.

Headless CMS

These are the new challenge. The CMS is completely separated from the frontend. The frontend might be built with React, Vue, or Next.js, and it just fetches content from the CMS via API.

Detecting the CMS in a headless setup is harder. Sometimes impossible from the frontend alone. You have to look at API endpoints, response headers from those endpoints, and data structure patterns.

Custom-Built Systems

Sometimes it's not a CMS at all. It's custom code. And that's okay – it's important to recognize when you can't identify something rather than making a wrong guess.

Building Your Own Detector

Want to build a CMS detector? Here's the basic algorithm I use:

1. Check for generator meta tag
   IF found: return CMS and version
   
2. Check HTTP headers
   IF found CMS-specific header: return CMS
   
3. Try common CMS paths
   IF WordPress path exists: return WordPress
   IF Joomla path exists: return Joomla
   (etc.)
   
4. Analyze HTML for patterns
   Search for common file paths
   Search for specific JavaScript/CSS
   IF patterns match known CMS: return CMS
   
5. Check REST API endpoints
   IF WordPress API responds: return WordPress
   (etc.)
   
6. If nothing matches: return "Unknown" or "Custom"

I've built this in Python, JavaScript, and PHP. The logic is basically the same.

Here's a super simple Python example:

import requests
from bs4 import BeautifulSoup
def detect_cms(url):
    # Fetch the page
    response = requests.get(url)
    html = response.text
    headers = response.headers
    
    # Check meta tag
    if 'generator' in html.lower():
        soup = BeautifulSoup(html, 'html.parser')
        meta = soup.find('meta', {'name': 'generator'})
        if meta:
            return meta.get('content')
    
    # Check for WordPress
    if '/wp-content/' in html or '/wp-includes/' in html:
        return 'WordPress'
    
    # Check for Shopify
    if 'cdn.shopify.com' in html:
        return 'Shopify'
    
    # Check for Wix
    if 'wixstatic.com' in html:
        return 'Wix'
    
    # Add more checks...
    
    return 'Unknown'

This is overly simplified, but you get the idea. Real detectors are more sophisticated, but the principle is the same: look for signatures.

The Ethics of CMS Detection

Quick sidebar: is CMS detection ethical? Yes. Absolutely. You're looking at publicly available information. It's no different than looking at a building and recognizing the architectural style.

However, what you do with that information matters. Using it to find vulnerabilities to attack sites? Not cool. Using it for competitive research, security auditing (with permission), or educational purposes? Totally fine.

I've been doing this professionally for years and never had an ethical issue. Just use common sense and don't be a jerk.

Tools I Actually Use

In real life, I rarely build detection from scratch. I use tools:

For Quick Checks:
- Wappalyzer (browser extension)
- BuiltWith.com
- WhatCMS.org

For Deeper Analysis:
- WPScan (WordPress-specific, command line)
- Nmap with http-enum script
- Custom scripts for specific use cases

For Bulk Analysis:
- BuiltWith API
- Custom Python scripts with headless browsers

The browser extensions are great for casual checking. The command-line tools are better for serious analysis or automated scanning.

Common Mistakes People Make

I've seen a lot of failed attempts at hiding CMSs. Here are the most common mistakes:

Mistake 1: Only Removing the Generator Tag

As I mentioned earlier, this is like removing one clue while leaving twenty others. Ineffective.

Mistake 2: Renaming Directories Without Understanding Dependencies

Renaming /wp-content/ breaks things unless you update all the references. Most people don't bother.

Mistake 3: Thinking Security Through Obscurity Works

Hiding your CMS doesn't make your site secure. Keeping it updated and properly configured does.

Mistake 4: Forgetting About HTTP Headers

People focus on the HTML and forget servers are chatty.

Mistake 5: Not Checking From Multiple Sources

Just because you removed signs on the homepage doesn't mean they're not on other pages, in your sitemap.xml, or in your RSS feed.

The Future of CMS Detection

Where is this heading? A few predictions:

More Headless Setups

As headless CMS becomes more popular, frontend detection will become harder. We'll need to rely more on API fingerprinting and server-side detection.

Better Obfuscation

Tools will emerge to better hide CMS signatures. But there will always be tells. You can't completely hide what you're built with.

AI-Powered Detection

Machine learning could analyze subtle patterns humans might miss. Imagine training a model on thousands of WordPress sites to recognize WordPress-specific coding patterns.

Behavioral Fingerprinting

Instead of looking for specific files, we might analyze how sites behave – response patterns, timing, cookie behavior – to identify the underlying technology.

Wrapping Up: Why This Matters

You might be wondering why anyone cares about CMS detection. Here's why I think it's important:

For Developers: Understanding how sites are built helps you learn and improve your own skills.

For Businesses: Knowing what your competitors use informs technology decisions.

For Security: Identifying outdated CMSs helps protect the web.

For Curiosity: Sometimes you just want to know how things work.

I've spent over a decade working with CMSs, and honestly, I still find CMS detection fascinating. Every site is a little puzzle. Some are easy, some are challenging, but they're all interesting.

The techniques I've shared here work today. Tomorrow, they might need adjustment. The web evolves. CMSs change. New platforms emerge. But the fundamental principle remains: every system leaves fingerprints. You just need to know where to look.

Now if you'll excuse me, I have about seventeen websites to analyze. Someone on Twitter is convinced they're all using custom frameworks, and I'm pretty sure at least half are WordPress. Time to prove it.

---

Got questions about CMS detection or want to share your own techniques? I'd love to hear them. Drop a comment below!