Free Website Tech Stack Checker — See What Any Site Is Built With

What Is a Tech Stack Checker?

A tech stack checker is a tool that analyzes a website and identifies the underlying technologies used to build and operate it. Every website relies on a combination of programming languages, frameworks, content management systems, analytics platforms, hosting providers, and third-party integrations. This combination is commonly referred to as the site's "tech stack." By examining HTTP response headers, HTML source patterns, JavaScript libraries, and other fingerprints, a tech stack checker can reveal what tools and platforms a company has chosen to power its online presence.

Technology detection matters because a company's tech stack tells you a great deal about its size, technical maturity, budget, and priorities. A business running on Shopify with Klaviyo and Google Analytics has very different needs than one built on a custom React application with Segment and Snowflake. Understanding these differences is essential for sales teams targeting the right prospects, agencies preparing informed pitches, and competitive analysts benchmarking their own infrastructure against industry peers.

Why Knowing a Website's Tech Stack Matters

There are several practical reasons to look up the technology behind a website. Each use case benefits from having accurate, up-to-date intelligence about what tools a company relies on.

• Sales Prospecting: If you sell a product that integrates with or replaces a specific technology, knowing which prospects use that technology lets you personalize your outreach. For example, if you sell a Shopify app, you can target only companies running Shopify stores. If you offer a faster alternative to a particular analytics tool, you can reach out to businesses currently using it with a compelling migration pitch. This level of targeting dramatically improves response rates compared to generic cold outreach.
• Competitive Analysis: Understanding what technologies your competitors use helps you evaluate their strengths and weaknesses. If a competitor recently adopted a new A/B testing platform, that signals investment in conversion optimization. If they switched CDN providers, it might indicate scaling challenges. Tracking technology changes over time gives you strategic visibility into competitor moves.
• Partnership Evaluation: Before integrating with another company or evaluating a potential technology partner, understanding their stack helps you assess compatibility. Knowing whether a partner uses REST or GraphQL APIs, what cloud provider they run on, or which authentication framework they employ can save months of integration headaches down the road.
• Investment Research: Venture capital firms and analysts use technographic data to evaluate startups and established companies. A company's technology choices reflect its engineering culture, scalability readiness, and operational costs. This information supplements traditional financial and market analysis.

How This Tool Detects Technologies

Our tech stack checker uses multiple detection methods to identify the technologies powering a website. Each method targets a different layer of the technology stack, and combining them produces a comprehensive profile.

• HTTP Header Analysis: When a web server responds to a request, it includes HTTP headers that often reveal the server software, CDN provider, caching layer, and security configurations. Headers like X-Powered-By, Server, and Via are direct indicators of backend technologies. Custom headers from platforms like Cloudflare, Vercel, and Netlify make CDN detection straightforward.
• HTML Pattern Matching: The HTML source of a page contains patterns unique to specific platforms. WordPress sites include wp-content paths, Shopify stores reference cdn.shopify.com, and Wix pages contain distinctive markup structures. By scanning the HTML for these known fingerprints, we can reliably identify the CMS, e-commerce platform, and many frontend frameworks in use.
• JavaScript Library Detection: Modern websites load numerous JavaScript files and define global variables that identify the libraries in use. React exposes __REACT_DEVTOOLS_GLOBAL_HOOK__, jQuery defines window.jQuery, and Google Analytics creates window.ga or window.gtag. Analyzing script URLs and known global objects reveals the analytics, tracking, and frontend libraries a site depends on.
• DNS and Infrastructure Signals: DNS records, SSL certificate details, and IP address ranges can indicate hosting providers and email services. A site resolving to AWS IP ranges, using Cloudflare nameservers, or having an SSL certificate issued by Let's Encrypt each provides a piece of the infrastructure puzzle.