The site is using Let's Encrypt for https. Currently there is a hard limit of 2000 subdomains per week, meaning there will be at most 2000 simultaneous connections!
It seems that Wildcard support is coming Jan 2018.
Looks interesting. Somehow it would not work on a image file.
Great job! Have you considered adding HTTPS support?
I like it!
Edit: How about support for HTTP/2 and TLS 1.3?
would you consider open sourcing this?
I cannot see a privacy policy, or any statement regarding the handling of the data flowing through this tool, nor any code which could be audited.
Inspired by https://medium.com/@shazow/ssh-how-does-it-even-9e43586e4ffc and ngrok, I made this SSH server that assigns a public url for each remote port forwarding request you make. Start a web server on 8080, then try this:
ssh -R 80:localhost:8080 serveo.net
It's an attempt to make port forwarding as easy as ngrok or localtunnel, but using the SSH client you already have.
Also includes HTTP inspection and replay like ngrok.