Flask
Flask is a Python micro web framework ideal for rapidly constructing web applications, offering minimalism, flexibility, and modularity.
About
Flask is a Python micro web framework ideal for rapidly constructing web applications, offering minimalism, flexibility, and modularity.
Categories: Web frameworks, Web servers
Quick facts
Detection methodology for Web frameworks
Server software identification reads the `Server` response header and (where exposed) version-specific markers in error pages. Cloudflare in front of nginx in front of Apache is the classic three-layer stack you'll see in the wild — we surface each layer separately so the actual origin server isn't masked by the edge layer.
How we detect Flask
Each signal alone is rarely conclusive — Sourcemap Explorer cross-references all of them and weights by confidence. You can reproduce any of these checks yourself in Chrome DevTools.
Server-side fingerprint: the response header reveals the technology behind the page. Visible in DevTools → Network → response headers.
Server: Werkzeug/?([\d\.]+)?
Implies
When Flaskis detected, Sourcemap Explorer also marks the following technologies as present (Wappalyzer's implies graph).
FAQ
How do I check if a website is using Flask?
Open the page in Chrome, click the Sourcemap Explorer toolbar icon, and read the Stack tab. The popup matches Flask's fingerprint signals (response headers, asset URL prefixes, runtime globals, sourcemap paths) and flags it whenever any combination is found. The same checks can be reproduced manually in DevTools — see the "How we detect" section above.
What Flask version can Sourcemap Explorer detect?
Flask ships as a hosted web frameworks rather than a bundled npm package, so version-specific detection isn't always possible. Where the platform leaks a version in response headers (`X-Powered-By`, `Server`, generator meta tags) we surface it; otherwise we report presence only.
Is Flask open source?
Yes, Flask is open source. The license details are listed on the official site (https://github.com/pallets/flask/), and the codebase typically lives on a public source-control host.
Where can I read more about Flask?
Official site: https://github.com/pallets/flask/. For Sourcemap Explorer's detection guide, see the deep-dive link below or the related guides in the cross-link section.
Keep reading on Sourcemap Explorer
Alternative tools
Detected by Sourcemap Explorer
Open the popup on any page running Flaskand you'll see the exact version pulled from the bundled package.json when sourcemaps are exposed.