Programming Language Detector — What Is a Website Built In?

Paste a URL. See whether the backend runs PHP, Python, Ruby, Java, Node.js, ASP.NET, Go, or another language — inferred from headers, cookies, and framework fingerprints. Free, no signup.

Try: php.net · python.org · rubyonrails.org · wordpress.org

Languages & Runtimes This Detector Identifies

DetectZeStack infers the backend language from server-side signals — headers, cookies, and the frameworks that imply a runtime.

PHPX-Powered-By, PHPSESSID
PythonDjango/Flask, gunicorn
Ruby_rails_session, Phusion
JavaJSESSIONID, Servlet headers
Node.jsconnect.sid, X-Powered-By: Express
ASP.NET / C#X-AspNet-Version, ASP.NET_SessionId
Goserver signatures
Perlmod_perl headers
ElixirPhoenix, _session cookie
ScalaPlay framework signatures
Laravel (PHP)laravel_session, XSRF-TOKEN
Django (Python)csrftoken, sessionid
Rails (Ruby)_session_id, x-runtime
Express (Node)X-Powered-By: Express
Spring (Java)JSESSIONID + Spring headers
+ morevia header & cookie signatures

How It Works

A site's backend language isn't shown on the page — but it leaks through three server-side channels.

Response headersX-Powered-By: PHP/8.2, X-AspNet-Version, Server, X-Runtime — direct runtime tells when not stripped.
Session cookiesPHPSESSID → PHP, JSESSIONID → Java, _rails_session → Ruby, connect.sid → Node.
Framework fingerprintsLaravel, Django, Rails, Spring, Express each imply their language even when headers are hidden.

Need This in Code? Use the API

Same detection, programmatic — profile a portfolio of sites, segment by stack, or audit a migration.

curl "https://detectzestack.com/analyze?url=wordpress.org" \
  | jq '.categories["Programming languages"]'

# Output:
# ["PHP"]

100 requests/month free — grab an API key. Paid plans from $9/month for 1,000 requests. Full docs: OpenAPI spec.

Frequently Asked Questions

How do I find out what language a website is built in?

Paste the URL into the detector above. It reads server headers, session cookies, and framework fingerprints to infer the backend language in a couple of seconds.

Can you really detect the backend language from outside?

Partially, and honestly. Languages leak via headers (X-Powered-By: PHP), cookie names (PHPSESSID, JSESSIONID, _rails_session), and frameworks. Sites that strip these can hide it — a "not detected" result is normal.

Is this language detector free?

Yes — free, no signup. For bulk or programmatic detection, grab a free API key (100 requests/month, no credit card), paid plans from $9/month.

Why does a site show no language?

Many sites strip X-Powered-By and Server headers for security, and fully static sites have no backend language at all. The detector reports nothing rather than guessing.

Does it detect the framework too?

Yes — Laravel, Django, Rails, Spring, and Express are detected and imply their language. For front-end frameworks, use the JavaScript framework detector.

Detect Backend Languages Programmatically

100 free API requests per month. No credit card.

Get Free API Key

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