There's this little gem that uses websocket tunnels for all those times only http is allowed. https://github.com/jpillora/chisel

A lot of modern websites rely on websockets for push notifications so they're usually open. It works wonderfully for things like public WiFi where all traffic is sent through an HTTP proxy and everything else blocked

my glorious corporate firewall doesn't allow any traffic other than on ports 80,443

inbound, outbound, or both?

only outbound connections permitted

I'd ask for approval in writing from my boss to play this game. If received, you could perfectly well set up a $6 digital ocean box and ask sshd to listen to 443. Then...

   ssh -R 443:localhost:3000 -N my_remote-server

is a perfectly good outbound connection?

Obviously, you'll want some iptables on the remote end or for your local box not to have anything valuable on it, but it will let you test webhooks.

I run an sshd on 443 for this reason. Helped me bypass some corporate firewalls in the past, very useful when you go onsite.