Testing various Irmin backend in the browser using the irmin-test package. See the results at https://patricoferris.github.io/irmin-browser-tests
If you want to take the irmin-server example for a spin (a client connecting over a websocket), you'll need to run an irmin-server on the appropriate port. This should do the trick:
dune exec -- irmin-server/examples/server.exe ws://localhost:9090/ws
Also note, Chrome seems to kill all of the websockets probably for security. Try it in Safari or Firefox. Happy Irmin-ing!