[natch]

Looks really cool.

Why are you using a URL in place of a domain name, in the invocation example? Seems confusing. I would expect to see just a domain name there. Although I wouldn't complain if it works with both a domain and a full URL, automatically stripping off the parts it doesn't need. Also seeing http:// instead of https:// is starting to feel strange these days, but I do realize both are still used and your tool works with both as it should.

Very nice readme! And nice to see it has a man page. I would leave out the "It's simple:" line because that tends to make less confident people (like new people just learning) blame themselves if they have problems, and then instead of giving you feedback they'll give up and move on.

[nodesocket]

Great job. Small nitpick. Agree —domain should probably be called —url instead. Domain implies no scheme.