How to Tell What CMS a Website Uses – A Complete Expert Guide

When you land on a website and wonder, “What CMS is this built on?” you’re tapping into a useful skill that anyone working in digital marketing, web design or SEO should master. Identifying the content management system (CMS) behind a site gives you insight into business technology stacks, competitor capabilities and potential development constraints. 

In this article I’ll walk you step-by-step through how to tell what CMS a website uses, why it matters, and the advanced techniques professionals use in 2025.

Why Knowing the CMS Matters

Understanding the CMS of a site provides multiple strategic advantages. First, if you’re a developer or agency prospecting clients you’ll immediately know the sort of technology you’ll deal with. Second, for SEO or digital marketing you’ll know how flexible the site is, how easy updates will be and what plugin ecosystem is available.

Third, from a security standpoint, knowing the CMS reveals whether the site is on a widely-used platform (which often means more frequent vulnerabilities but also more support). According to recent tech-stack scans, over 43% of all websites use one of the top three CMS platforms. So mastering this detection skill is incredibly valuable.

Key Methods to Detect a CMS

Below are the most reliable methods—starting with the easiest and moving into more technical territory. A seasoned professional uses a combination of these.

1. Automated detection tools
   Use online scanners that check the URL and present results instantly. For example, tools can detect over 1,200 CMS platforms by identifying code signatures and paths.
   They work by matching known folder structures, meta generator tags, header responses and script patterns against databases of CMS fingerprints.
2. Browser extensions
   Install a tech-stack profiler extension (such as a “What CMS Is This?” or “Wappalyzer” add-on). These tools reveal a CMS, analytics libraries, frameworks and even plugin technologies in one click.
   When you browse a site, the extension icon lights up and shows “WordPress 6.4”, or “Drupal 10”, etc. It saves you manual digging.
3. Inspect the page source
   Open the webpage, right-click and choose “View Page Source” (or press Ctrl+U). Then search for clues such as:

• A meta tag: <meta name=”generator” content=”WordPress 6.4″ />

• Folder paths like wp-content/ or wp-includes/ which immediately indicate WordPress.

• Other CMS keywords: sites/default/ (Drupal), administrator/ (Joomla)
  If you spot these patterns, you’ve identified the CMS without running any external tool.

4. Check login and admin URL paths
   Nearly all major CMS platforms use standard default login pages. For example:

• For WordPress: yourdomain.com/wp-admin/

• For Joomla: yourdomain.com/administrator/

• For Drupal: yourdomain.com/user/login
  If you access the URL and it prompts a login page with CMS-branded text, you’re done.

5. Examine URL and file-path patterns
   Look at the website’s URL structure:

• WordPress often uses parameters like ?p=123 or friendly permalinks such as /2025/10/title/

• Joomla uses index.php?option=com_content&view=article&id=123
  Recognizable query parameters or folder names help determine the CMS.

6. Review the robots.txt file
   Navigate to yourdomain.com/robots.txt. You might see paths such as:
   Disallow: /wp-admin/
   Allow: /wp-admin/admin-ajax.php
   Which clearly point to WordPress. Other CMSs may list their specific admin folders here.
7. Check HTTP headers and cookies
   HTTP headers returned by the server may leak the CMS type or version in X-Powered-By: or similar fields. Cookies might include names like wordpress_logged_in_ or joomla_user_state. These subtle hints signal the underlying CMS.

Step-By-Step Approach You Can Use Right Now

Here’s a workflow I use as a professional auditor:

1. Enter the website URL in a CMS detection tool and record the result.

2. Activate a browser technology profiler extension and verify the CMS shown matches the tool result.

3. View page source and search for “generator”, “wp-content”, “sites/default” or other keywords.

4. Try standard login URLs (e.g., /wp-admin/, /administrator/) and observe what comes up.

5. Open robots.txt, look for CMS-specific paths.

6. Inspect HTTP headers or cookies for CMS-keywords.

7. If all methods fail and it seems custom-built, assume a proprietary CMS and proceed accordingly.

Following this method gives you results over 90% of the time—most platforms leave some trace unless heavily obfuscated.

Common CMS Platforms and Their Fingerprints

To help you identify quickly, here are some of the most common CMSs and how they typically appear:

• WordPress: Look for wp-content/, wp-includes/, login URL /wp-admin/, meta generator tag.

• Drupal: Look for sites/default/, URL pattern /node/123, login path /user/login.

• Joomla: Look for /administrator/, URLs with option=com_content, meta generator.

• Shopify: Usually hosted on myshopify.com, folder structure less obvious, but tool detection works well.

• Squarespace / Wix: These often hide code clues but the URL will contain builder-specific patterns and the detection tools generally identify them.

When Manual Methods Don’t Work

Some websites intentionally hide their CMS—for example, by removing generator meta tags or renaming admin URLs. In such cases:

• Use advanced fingerprinting via browser extensions or command-line tools like WhatWeb or CMSmap. These tools use pattern matching and heuristics beyond simple tag detection.

• Look at network requests for vendor libraries or JavaScript files unique to specific CMSs.

• Compare the site’s HTML structure with known templates of major CMSs (many theme marketplaces publish theme screenshots).

• Use batch detection or API-based tools if you’re analysing many sites at once.

Why Accuracy Matters in 2025

With the shift toward headless CMSs, PWAs (Progressive Web Apps), and custom-built frameworks, simple detection methods are less effective. A recent article shows that modern detection tools must combine HTML scanning, header analysis and machine-learning classification to detect over 1,000 CMS variants.

From a security and migration planning perspective, knowing the exact CMS version and configuration matters. Older versions may no longer receive patches. If you’re advising a company or planning a move, early detection saves hours of effort.

Practical Use Cases for CMS Detection

• Competitive research: Knowing that a top competitor uses WordPress vs a custom CMS gives you insight into their agility and flexibility.

• Client onboarding: If a client’s website uses an outdated CMS, you can better assess upgrade or rebuild strategy.

• Lead generation for agencies: Detect sites still using deprecated CMSs and target them for pitch.

• Security audits: If you identify the CMS and version, you can check for known vulnerabilities or missing updates.

• Migration planning: If you’ll migrate content to a new CMS, know what you’re working with originally.

Tips and Best Practices

• Always combine at least two detection methods for higher confidence.

• Be aware that custom-built sites may masquerade as standard CMSs—if detection fails, assume proprietary.

• Use up-to-date detection tools and browser extensions, as new CMSs and patterns emerge regularly.

• Consider the ethics: identifying CMS is fine, but probing vulnerabilities without permission is not.

• If you discover the CMS type but not the version, err on the side of caution when advising upgrades or security fixes.

Conclusion

Being able to tell what CMS a website uses is a crucial skill for marketers, developers, analysts and agencies. By combining automated tools, browser extensions and manual inspection you can detect the platform behind most sites quickly and accurately. 

Knowing a site’s CMS gives you strategic advantages in client work, competitive audits and migration planning. Stay up-to-date with detection techniques and you’ll stay ahead of the curve in 2025 and beyond.