Google has begun supporting HTTP/3 in nightly builds. Chrome Canary is an official experimental channel that provides binaries to allow you to test new features such as HTTP/3. Nightly builds may have some stability issues that you should keep in mind when testing.
HTTP/3 is not enabled by default. Chrome must be launched with the
--enable-quic --quic-version=h3-27 flags to work.
Running on Windows
If installed in the default location, starting Chrome with the correct flags is done by running the following commands in a command prompt:
cd C:\Users\$USER\AppData\Local\Google\Chrome SxS\Applicationchrome.exe --enable-quic --quic-version=h3-27
(Replace $USER with the name of your account on Windows.)
Running on MacOS X
If installed in the default location, starting Chrome with the correct flags is done by running the following command in a terminal:
/Applications/Google\ Chrome\ Canary.app/Contents/MacOS/Google\ Chrome\ Canary --enable-quic --quic-version=h3-27