Tunneling isn't that big of a toll on resource, it doesn't require storage/disk space nor compute power (CPU chips), all it needs is ingress/egress (spare bandwidth). A non-profit or decent business in telco can easily offer it, consider that many hosting companies offer entire package in free tier today (compute + disk + egress).
For several years, ngrok was practically free, only recently they've started monetizing once it gained popularity.
I don't really get how the developer can run the project free of charge without monetization options. Does this solely rely on donors?
Tunneling isn't that big of a toll on resource, it doesn't require storage/disk space nor compute power (CPU chips), all it needs is ingress/egress (spare bandwidth). A non-profit or decent business in telco can easily offer it, consider that many hosting companies offer entire package in free tier today (compute + disk + egress).
For several years, ngrok was practically free, only recently they've started monetizing once it gained popularity.
Gotta say, this is amazing, exactly what I needed.