How to Check What Technology a Website Uses (5 Free Methods)

Ever looked at a website and wondered what technology powers it? Whether you’re researching competitors, preparing for a sales call, or just curious, there are several free ways to find out.

In this guide, I’ll walk you through five methods to check what technology any website uses—from quick browser extensions to more technical approaches.

Method 1: Browser Extensions (Quickest Option)

Browser extensions are the fastest way to check individual websites. Install once, and you can see technology information for any site you visit.

How They Work

These extensions analyze the webpage you’re viewing—checking the source code, JavaScript files, HTTP headers, and other signals—then match what they find against a database of known technology signatures.

Popular Options

Wappalyzer – One of the most popular choices. Shows detected technologies in a popup when you click the icon. The free tier works well for occasional lookups.

BuiltWith – Another established option with good technology coverage. Shows results in a sidebar when activated.

TechLeads.fyi Extension – Offers unlimited free lookups while browsing, plus integration with lead list building if you have an account.

Limitations

• Only works for sites you visit individually
• Can’t search across multiple sites
• Free tiers may have monthly limits

Best For

Quick checks before sales calls, competitive research on specific sites, satisfying curiosity about how a site is built.

Method 2: View Page Source (Free, No Tools Needed)

You don’t need any tools for this one—just your browser. The source code of any webpage is publicly viewable.

How to Do It

1. Right-click anywhere on the webpage
2. Select “View Page Source” (or press Ctrl+U / Cmd+Option+U)
3. Search through the code for technology clues

What to Look For

Meta tags: Look for <meta name="generator" content="...">. WordPress sites often include this, revealing the CMS and sometimes the theme.

Script tags: Search for <script and look at the src URLs. You’ll see references to Google Analytics, React, jQuery, and other JavaScript libraries.

Link tags: CSS frameworks like Bootstrap or Tailwind are often identifiable by their stylesheet URLs.

Comments: Developers sometimes leave comments that reveal the platform. Search for <!-- to find them.

Limitations

• Requires some technical knowledge to interpret
• Time-consuming for checking multiple sites
• May miss backend technologies that don’t show in frontend code

Best For

Developers who want detailed information, verifying what browser extensions report, learning how sites are built.

Method 3: HTTP Headers (More Technical)

HTTP headers contain metadata about how a server responds to requests. Many technologies leave fingerprints here.

How to Do It

1. Open your browser’s Developer Tools (F12 or right-click → Inspect)
2. Go to the Network tab
3. Reload the page
4. Click on the main document request
5. Look at the Response Headers

What to Look For

Server: Often reveals the web server (nginx, Apache, etc.) and sometimes the platform.

X-Powered-By: May show the backend technology (PHP, ASP.NET, Express, etc.).

Set-Cookie: Cookie names often reveal platforms. Shopify, WordPress, and others have distinctive cookie patterns.

Custom headers: Some platforms add their own headers (X-Shopify-Stage, X-WP-Engine, etc.).

Limitations

• Requires technical knowledge
• Many sites hide or modify headers for security
• Not comprehensive—only shows server-side hints

Best For

Technical users investigating server-side technologies, security researchers, developers debugging.

Method 4: URL Pattern Analysis (Simple and Free)

Different platforms create distinctive URL patterns. With practice, you can often identify technologies just by looking at URLs.

Common Patterns

Shopify: URLs often include /collections/, /products/, or the domain ends in .myshopify.com for development stores.

WordPress: Look for /wp-content/, /wp-includes/, or /wp-admin/ in resource URLs.

Squarespace: Static files often come from static1.squarespace.com.

Webflow: Assets from assets.website-files.com or webflow.io domains.

How to Do It

1. Open Developer Tools → Network tab
2. Reload and look at the URLs of loaded resources
3. Or simply check the URL bar and site navigation patterns

Limitations

• Only works for platforms with distinctive URLs
• Custom configurations may hide these patterns
• Requires familiarity with common patterns

Best For

Quick platform identification, training yourself to recognize common technologies, situations where extensions aren’t available.

Method 5: robots.txt and sitemap.xml (Hidden Clues)

These standard files often reveal platform information that isn’t visible on the main site.

How to Do It

1. Add /robots.txt to any website URL (e.g., example.com/robots.txt)
2. Add /sitemap.xml to check the sitemap (e.g., example.com/sitemap.xml)
3. Look for platform-specific paths and patterns

What You’ll Find

WordPress: robots.txt often disallows /wp-admin/ or references /wp-includes/. Sitemaps come from plugins like Yoast.

Shopify: You’ll see paths like /admin, /cart, and Shopify-specific sitemap structures.

CMS platforms: Each has distinctive admin paths and directory structures they block or expose.

Limitations

• Not all sites have these files
• Some platforms hide telltale signs
• Requires checking multiple files manually

Best For

Quick CMS identification, finding blocked admin paths, situations where source code isn’t revealing.

When Free Methods Aren’t Enough

These five methods work well for checking individual websites. But they have a fundamental limitation: they only work one site at a time.

If you need to:

• Find all websites using a specific technology
• Build prospecting lists based on tech stack
• Export data for use in your CRM
• Add contact information to your technology data

You’ll need a technology database. Tools like TechLeads.fyi have already crawled hundreds of millions of websites and let you search, filter, and export the results.

The free methods are great for understanding how technology detection works and for occasional lookups. For serious prospecting, the paid tools pay for themselves in time saved.

Quick Reference: Which Method to Use

Situation	Best Method
Quick check before a sales call	Browser extension
Detailed technical analysis	View source + HTTP headers
No tools available	URL patterns + robots.txt
Verifying extension results	View source
Bulk research / lead generation	Technology database (TechLeads.fyi)

Now you have five free ways to check what technology any website uses. Start with browser extensions for convenience, and use the technical methods when you need more detail.

Need to search across millions of websites by technology? Try TechLeads.fyi for bulk technology research and lead generation.