I run another alternative serveo.net. As far as I can tell, it was the first or second to use SSH for the client/transport. It was down for a couple years but is running again since March.
Good to know that it is up again.
Love the zrok mention (I work on the parent project). One note, 0.4 is now released and thus UDP tunnels supported :)
Thanks. Will update it. Definitely Zrok is a great self-hosted alternative.