Website stack lookup
What is this website built with?
I built WhosBuilt for the question I run into all the time: what stack is this site using, and where did that answer come from?
Page code
HTML markers, generator tags, script URLs, CSS paths, JSON-LD, and frontend framework clues.
Network clues
Response headers, CDN headers, server names, caching layers, and redirect behavior.
DNS and hosting
Name servers, A and AAAA records, MX records, IP network, hosting provider, and email provider.
Ownership context
WHOIS, registrar, SSL issuer, public org data, footer credits, humans.txt, and about-page links.
The short answer
You can usually tell what a website is built with by checking the page source, the HTTP response, and the domain records. One layer is not enough. A React site can sit behind Cloudflare, ship from Vercel, use Google Workspace for email, and still have a WordPress blog somewhere else.
WhosBuilt checks those layers together. I care less about guessing a logo and more about showing the clue that led to the answer.
How I would check it manually
I start with the page source because that is where a lot of stack clues are exposed. A site might show WordPress, Shopify, Next.js, Nuxt, Vite, Astro, Webflow, analytics scripts, or a generator tag without trying to hide anything.
Then I check the network and infrastructure layer. Headers can point to Vercel, Netlify, Cloudflare, nginx, Caddy, or a managed platform. DNS and IP records can show where the site is hosted and which services handle email.
WhosBuilt puts those checks in one scan. I do not need browser extensions, manual WHOIS tabs, or a text file full of copied headers.
What you get back
The useful answer is not a logo wall. I want the evidence: detected technologies, HTTP headers, DNS records, SSL issuer, registrar, hosting clues, and ownership signals in the same report.
If the goal is outreach, due diligence, competitor research, or planning a rebuild, that context matters more than guessing the framework.
What it cannot know
Some stack choices are private. A static site can hide the CMS that produced it. A proxy can hide the origin server. A company can use one platform for the marketing site and another one for the app.
That is why I show the evidence instead of one overconfident label. If the clues point to Cloudflare and Vercel, I want both. If the generator tag is missing, I would rather leave that blank than invent an answer.
If you mainly care about infrastructure, the hosting lookup page goes deeper on that.