Happy Eyeballs Version 3
QUIC vs. TLS/TCP Test

Our specialized web server introduces targeted, artificial delays during the transport-layer protocol handshake (based on the TLS SNI). This capability allows us to selectively delay either the TLS/TCP or the QUIC handshake.

To signal HTTP/3 (QUIC) availability, our DNS nameserver responds with HTTPS resource records for all test domains. The specific contents of these HTTPS records can be customized in the settings.

Note: For the test to function properly, your browser must query and respect these records. You can verify your browser's compatibility using our HTTP/3 availability test .

During the test, the browser establishes connections for a range of transport-layer delays. This allows you to observe if and how the browser handles the Happy Eyeballs version 3 race between TLS/TCP and QUIC.

We randomize domains to try to prevent caching effects on the browser's side as much as possible. Furthermore, we aggressively close connections on the server side after every request, forcing the browser to perform a fresh handshake for each new test.