Microsoft ASP.NET

Server-side fingerprint: the response header reveals the technology behind the page. Visible in DevTools → Network → response headers.

X-AspNet-Version: (.+)

X-Powered-By: ^ASP\.NET

set-cookie: \.AspNetCore

Cookies set by the platform. Visible in DevTools → Application → Cookies.

ASPSESSION

ASP\.NET_SessionId

\.ASPXAUTH

Substring or regex match against the page HTML — typically a unique class, comment marker, or asset path.

<input[^>]+name="__VIEWSTATE

The page URL itself follows a known pattern (vanity slugs, embeds, hosting URLs).

\.aspx?(?:$|\?)

A DOM selector that only this technology's pages render. Verified at runtime by the content script.

input[name*='__VIEWSTATE']

How do I check if a website is using Microsoft ASP.NET?

Open the page in Chrome, click the Sourcemap Explorer toolbar icon, and read the Stack tab. The popup matches Microsoft ASP.NET'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 Microsoft ASP.NET version can Sourcemap Explorer detect?

Microsoft ASP.NET 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.

Where can I read more about Microsoft ASP.NET?

Official site: https://www.asp.net. For Sourcemap Explorer's detection guide, see the deep-dive link below or the related guides in the cross-link section.