What are some alternatives?
When comparing Portmap.io and ngrok, you can also consider the following products
Serveo - Use SSH to expose local servers over the internet and inspect and replay HTTP traffic.
Pagekite - Bring your localhost servers on-line.
sish - An open source serveo/ngrok alternative. HTTP(S)/WS(S)/TCP Tunnels to localhost using only SSH.
Cylance - Cylance is an endpoint security platform that detects, prevents and blocks threats.
Forward - The easiest way to share localhost over the web.
LocalXpose - P2P reverse proxy platform that enables you to expose your localhost to the internet.