Can I talk QUIC right now?
Test method: click the button below to test QUIC connectivity. This makes a simple HEAD request using the Fetch API.
Explanation: Detecting QUIC usage at the app level is not so simple, due to the way QUIC and Alt-Svc work together. There is a W3 effort to expose protocol information by means of the Resource Timing attribute nextHopProtocol. However, implementations have not fully rolled out support for this; currently it is supported in Firefox 51+ only (Chrome has stated an intent to implement). In the meantime the same type of information is exposed in Chrome's window.chrome.loadTimes() structure. Other browsers are out of luck altogether.