Website Technology Checker
Enter any website and see what it is built with: the CMS, JavaScript frameworks, analytics, tag managers, CDN, hosting, server and more, with version numbers where they show, plus SEO and security observations.
- 150+ technologies recognised
- Versions, evidence and confidence
- Security headers check
Found WordPress or a heavy script stack? Follow up with the Website Performance Checker or the Meta Tag Checker.
The technologies behind a website
The checker reads the page's HTML, the files it loads, its response headers and its cookie names.
CMS and platforms
WordPress, Drupal, Joomla, Shopify, Wix, Squarespace, Webflow, Ghost, Magento and WooCommerce, with versions when the site reveals them.
Frameworks and libraries
React, Next.js, Vue, Nuxt, Angular, Svelte, Astro, jQuery, Bootstrap, Tailwind CSS and many more.
Analytics and tracking
Google Analytics 4, Tag Manager, Hotjar, Clarity, Meta Pixel, LinkedIn Insight Tag, TikTok Pixel and other measurement tools.
CDN, hosting and servers
Cloudflare, CloudFront, Fastly, Vercel, Netlify, Nginx, Apache, LiteSpeed and the programming language behind the site.
SEO tools
Yoast SEO, Rank Math, All in One SEO, JSON-LD structured data, Open Graph tags and AMP.
Security and consent
reCAPTCHA, Turnstile, cookie consent tools, payment gateways and the security headers a server sends.
What a technology tells you about SEO
The stack points to the problems to look for first.
| If you see | Look for | Why |
|---|---|---|
| WordPress | Plugins, theme bloat, permalinks | Slow pages and duplicate URLs are the usual issues. An SEO plugin handles titles, canonicals and sitemaps. |
| Shopify | Duplicate product URLs | Products open under /collections/ and /products/ paths. Canonical tags must point to one. |
| React or Vue without Next or Nuxt | Rendering | Content built in the browser can be indexed late or not at all. |
| Several analytics and ad tags | Page speed | Every tag is JavaScript that delays the page. |
| Old jQuery or PHP versions | Security and speed | Unsupported versions get no fixes and slow the page. |
| No CDN | Server response time | Visitors far from the server wait longer. |
How to check what a website is built with
Three steps from a URL to a stack report.
Enter a URL
Paste any public website address, or paste the page's HTML if it isn't live.
Read the stack
See the technologies by category, with a version, a confidence level and where each was found.
Act on the notes
Work through the SEO and security observations, then run the performance and meta tag checks.
What detection can and can't tell you
A technology checker reads public clues. Some things stay hidden.
Hidden stacks
A site can hide its CMS, remove version numbers or serve scripts from its own domain, so a missing item means unknown, not absent.
Consent banners
Many tools only load after a visitor accepts cookies, so they may not show here.
Server-side tools
Server-side analytics, databases and back-office systems leave few traces in a page.
Confidence levels
Certain means a strong signal such as a header or generator tag. Likely and possible rest on weaker hints.
Competitor research
Checking competitors' stacks shows the tools and platforms your market uses.
Re-check after changes
Run it after a migration or plugin clean-up to confirm the old tools are gone.
What a website technology checker finds and why the stack matters
A website technology checker, also called a tech stack detector, works out what a site is built with. It reads the page's HTML, the files the page loads, the response headers and the cookie names, then matches them against known fingerprints. A /wp-content/ path points to WordPress, a Server header may name Nginx or Apache, a script address can reveal a framework, and a tag manager snippet shows which analytics are wired in.
The stack matters for SEO because it decides which problems are likely. A JavaScript framework without server-side rendering depends on Google rendering the page, which Google describes as a separate phase that happens after crawling, so server-side or pre-rendering is still a good approach. A WordPress site often needs a look at plugins and duplicate URLs. A store on a hosted platform has its own URL patterns and canonical behaviour. Knowing the platform before an audit saves time.
Detection is evidence, not proof. This tool shows where each match was found and how confident it is. It sees only what is public. A site can hide its CMS, serve scripts from its own domain, load tools after a consent click or run them on the server, so a missing technology means unknown, not absent. It also adds security notes, such as old PHP or jQuery versions and missing security headers, but it does not scan for vulnerabilities.
When to check what a website is built with
Use it at the start of any audit, and whenever you need to know what you are working with.
Before starting an SEO audit
Find the CMS, framework, CDN and tag setup first. They tell you which issues to look for, such as plugin bloat on WordPress or rendering on a JavaScript app.
To study a competitor
See which platform, e-commerce system, analytics and marketing tools competing sites use. It only reads what any visitor can see, so it is safe to run on any public page.
When inheriting a site
Get a quick inventory of an unfamiliar site: platform, version clues, analytics, tag managers and scripts that nobody remembers adding.
After a migration or clean-up
Confirm that the old platform, tracking tags or plugins are gone and the new ones are present. Leftover scripts from a previous setup are common after a move.
To spot outdated components
Version numbers in headers and script files show old PHP or jQuery releases that no longer get security fixes, and they point to a conversation with the host or developer.
Before choosing tools or developers
Check how a site you admire is built before copying the approach. The stack shapes cost, speed and the SEO features available.
Tech stack mistakes and how to fix them
Most of these are choices that look harmless in a project plan and show up later in speed and indexing.
Treating a missing item as proof
What goes wrong: A technology that does not appear in the results may still be in use. Consent banners, tag managers, server-side tools and renamed paths all hide things from outside detection.
The fix: Read an absence as unknown. Confirm with the site owner, the tag manager container or a look at the network requests before you report that a tool is not installed.
Client-side rendering with no fallback
What goes wrong: A React or Vue site that builds all content in the browser relies on Google rendering it later. Not every crawler can run JavaScript at all.
The fix: Use server-side rendering or pre-rendering for important pages, such as Next.js or Nuxt for those frameworks, and make sure key content and links are in the HTML response.
Overlapping plugins and tags
What goes wrong: Two SEO plugins, several analytics scripts or tracking tags added both directly and through a tag manager create duplicate tags, double-counted data and extra load time.
The fix: Keep one plugin or tool per job, audit the tag manager container, and remove tags that are no longer used. Re-run the check to see that the old ones are gone.
Running unsupported PHP or old libraries
What goes wrong: PHP versions past their security support, or very old jQuery, no longer receive fixes. The version may show in a header or script name, so attackers can see it too.
The fix: Ask the host to move the site to a supported PHP release after testing plugins, update or remove old libraries, and hide version banners as a small extra, not as the fix.
No CDN for a spread-out audience
What goes wrong: Serving every file from one distant server makes visitors far from it wait longer. Static files such as images, CSS and JavaScript are the easy part to move.
The fix: Put a CDN in front of the site and cache static files with long lifetimes. Then compare the server response before and after with the Website Performance Checker.
Trusting generator tags too much
What goes wrong: A generator meta tag or script name can be removed, faked or left over from an old setup, so a single clue may point to the wrong platform or version.
The fix: Check the confidence level and the evidence for each result. A strong signal such as a header or generator tag counts for more than one weak hint.
Tech stack terms explained
- Tech stack
- The set of technologies a site is built and run on: CMS or framework, programming language, server, CDN, analytics, tag manager and other scripts.
- Fingerprint
- A recognisable trace a technology leaves, such as a file path, a header value, a cookie name or a snippet in a script. Detection tools match fingerprints to a list of known technologies.
- CMS (content management system)
- Software for creating and managing site content without writing code for each page, such as WordPress, Drupal, Joomla or Shopify.
- Generator meta tag
- A
meta name="generator"tag some systems add to the page head, naming the software and sometimes its version. It is easy to remove, so its absence proves nothing. - Tag manager
- A system that loads analytics, advertising and other tags through one container script. Tools added this way may not appear in the page source.
- CDN (content delivery network)
- A network of servers that caches and delivers your files from locations close to visitors. It often adds its own headers, which helps detection.
- Server-side rendering (SSR)
- Building the page HTML on the server so content and links are in the first response. It contrasts with client-side rendering, where JavaScript builds the page in the browser.
- Headless CMS
- A content system that delivers content through an API to a separate front end. Because the front end can be anything, the CMS often leaves few traces on the public page.
Related tools, guides and services
Once you know the stack, check what it produces. These tools take the next step.
WordPress Theme & Plugin Detector
If the site runs WordPress, list its theme and plugins and check each for updates.
ToolWebsite Performance Checker
Measure server response, page weight and caching for the stack you have found.
ToolSecurity Headers Checker
Grade the security headers and cookie flags the server sends.
ToolMeta Tag Checker
Audit the titles, descriptions, canonical and social tags your platform outputs.
GuideTechnical vs complete SEO audit
See where checking the platform and stack fits within the different audit types.
ServiceTechnical SEO service
Get rendering, crawling and platform-specific problems found and fixed.
Built by
Madhav Kushwaha
SEO, AEO, GEO & Digital Marketing Consultant in Kathmandu, Nepal, and trainer at ODcrU Academy and TechAxis Institute. Before I audit a site, I want to know what it runs on, because the platform decides which problems are likely. I built this checker to answer that in one click, and to point out the stack choices that cause SEO and speed trouble.
Website Technology Checker: Frequently Asked Questions
More free SEO tools
Knowing the stack explains many SEO and speed problems. These tools check what it produces.