Same here. We use a subdomain with HTTPS that points to 127.0.0.1, and a WebSockets-Server on our clients machines. We install the private key on each machine f

Same here. We use a subdomain with HTTPS that points to 127.0.0.1, and a WebSockets-Server on our clients machines. We install the private key on each machine for this to work... yeah. It's always a nightmare, when a browser-upgrade comes along and changes something. Currently the following connections work: "wss://localhost.example.com:4321/somepath", // Mac: Chrome, Safari, FF "wss://localhost:4321/somepath", // Win: Chrome, FF "wss://127.0.0.1:4320/somepath" // Win: EDGE, IE11, IE10 Some other combinations are possible, that's just what I know we use atm. The worst thing is: I didn't find a way to catch connection-errors to these URLs. So I have to use timeouts, and try all of them... (or decide by User-Agent which URLs to try.) I wish there would be some kind of standard that solves this problem.