GF.dev HTTP/3 & QUIC Check

A free web tool that checks whether a server advertises HTTP/3 through its Alt-Svc header.

FreeProprietaryWeb

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About GF.dev HTTP/3 & QUIC Check

The HTTP/3 & QUIC Check is one of the GF.dev Geek Tools. It fetches a site's response headers and looks for the Alt-Svc directive, which tells browsers that the site can be reached over HTTP/3 (h3), usually on UDP port 443.

It checks the advertisement only and does not open an actual QUIC connection, so it confirms configuration rather than proving that HTTP/3 traffic works end to end. The page includes a short FAQ and links to a guide on enabling HTTP/2 and HTTP/3.

Strengths

  • Fast check for the Alt-Svc header
  • Nothing to install
  • Linked guide on enabling HTTP/3

Limitations

  • Does not test a real QUIC connection
  • Only checks servers reachable from the internet

Details

Pricing
FreeFree to use in the browser.
License
Proprietary
Developer
GF.dev
Platforms
Web
How it runs
Web application
Works offline
No
Best suited for
Confirming a site advertises HTTP/3 after a server or CDN change
Categories
Website testing
Last verified
Added
Provenance
Selected from the TechWalrus Resource Hub (Website Checkers & Audit Tools); facts checked against the developer's own pages, 2 sources on file.

Report a wrong fact or a dead link on this listing