Happy Eyeballs Webtester

HTTP/3 Availability Test

Test Repetitions:

Auto Transmit Results

Device and user information for easier debugging (optional - please update auto-filled data if incorrect)

Test Run #	Started at

Currently we collect the measured results together with userAgent, and vendor information. We do not collect or store your IP addresses as part of this measurement. If you want to help us to interpret the results you can describe the network environment as part of the device and user information input field. Measurement results are not transmitted automatically at the end of it. If you want to enable this feature, check the "Auto Transmit Results" box. If it's not checked you can transmit your results after the measurement ended.

Measurement Information

We operate a web server with HTTP/3 (QUIC) enabled. A subset of the test domains pointing to this server publish an HTTPS DNS record (HTTPS RR) that includes the h3 protocol in the alpn parameter. Additionally, certain paths on the server respond with an Alt-Svc header advertising HTTP/3 availability. The different test scenarios combine these domains and paths in various permutations.

We randomize domains in order to prevent caching effects on the browsers side. However, the web server is only assigned a single IP address. Clients that cache connection information on a per-address basis rather than a per-domain basis may therefore produce skewed results in subsequent test runs.

Developed by Patrick Sattler. Hosted on infrastructure of

Happy Eyeballs Webtester

HTTP/3 Availability Test

Collected Data

Measurement Information