Your mobile experience is quite jarring (the way you did your menu). I'd suggest not removing the other menu and just having two different menus and toggling the other sliding in. Didn't check the code but that's probably it, the menu getting removed and the content jumping up

Thanks, I've updated it to a floating menu that doesn't move content when its opened and did a minor revamp of the mobile experience of the site

Maybe it's a case of "If you have to ask what it does it's not for you", but from the expose webpage it is not clear to me at all what it does.

It will give a server (website or api) you have running on your local machine a public url.

Like @beaconstudio below mentioned it could be used to test webhooks. Other uses are testing local sites on mobile devices, like I just did to give the mobile experience of expose.sh a revamp. Its faster than running adb, rooting your phone or connecting a cable and doing mobile debugging.

There are other tools, although expose.sh is focused purely on http/https and not other protocols, this makes the syntax a bit easier as you don't have to specify a protocol, just a port i.e. "expose 80" instead of "ngrok http 80" (using ngrok as an example).

I've used similar services for Web hooks - if you're developing eg. a slack bot you'd have to deploy to a public url constantly without a tool like this, which shows down development considerably.

Looks like a competitor to ngrok.

Author of the article here. Good point! I think going solo can also provide peace of mind, in a way.