What is this website built with? How to find any site's tech stack

Maybe you like a site and want to know how it was made. Maybe you’re checking a supplier, sizing up a competitor, or wondering whether a shop runs on a platform you trust. Either way, most of a website’s technology is visible from the outside, if you know where to look.

Everything below works in any desktop browser, without installing anything.

Where technology shows itself

Software leaves fingerprints in three places: the page source, the response headers and the addresses a page loads files from. You don’t need to understand the code; you only need to recognise a few patterns.

1. The page source

Open the page and view its source with Ctrl+U (Cmd+Option+U on a Mac). Then search with Ctrl+F for the patterns below.

Generator tags. Many content management systems and site builders announce themselves in a <meta name="generator"> tag near the top:

Generator tags can be removed, so their absence means little. Their presence is a strong clue.

File paths. Frameworks put their files in recognisable folders:

Markup. Some tools mark the elements they create. Pages built with Vue often carry attributes starting with data-v-; Webflow sites carry data-wf-site.

2. The response headers

Every page arrives with headers you don’t normally see. Open the developer tools (F12), choose the Network tab, reload the page, click the first request and read the Response headers.

A few common ones:

Headers are good evidence of hosting and delivery, which rarely shows anywhere else.

3. The scripts it loads

Payment providers, analytics and chat widgets almost always load a script from their own address. In the page source, search for <script and look at the src addresses:

For a shop, this is especially useful: it tells you which payment provider will actually handle your money, which matters for buyer protection.

Where the method stops

Reading a site from the outside has honest limits:

• What runs on the server stays hidden. Databases, back-end languages and internal tools leave no trace unless the site chooses to show them.
• Apps drawn by JavaScript show less. Many modern sites send an almost empty page and build everything in the browser. The page source then contains little more than a script address. Some fingerprints only appear in those scripts.
• Fingerprints can be removed or faked. Generator tags can be deleted; headers can be changed. Several independent clues agreeing are much stronger than one.
• “Not found” isn’t “not used”. A tool that isn’t in a list of fingerprints simply isn’t recognised.

Tech stack and AI builders

The same method answers another common question: was this site made with an AI site builder? Builders such as Lovable, Bolt.new and v0 leave their own fingerprints (scripts, tags, hosting addresses), covered in our guide on how to tell if a website was built with AI.

Skip the detective work: the Tech Stack Checker reads the page, the headers and the scripts for you, and shows each technology with the line or header it was found in.