localtunnel's server needs random ports per client. That doesn't work on Fly.io or behind strict firewalls.
We rewrote it in TypeScript and added multiplexing over a single port. Open-source and 100% self-hostable.
Public instance at *.pipenet.dev if you don't want to self-host.
Built at Glama for our MCP Inspector, but it's a generic tunnel with no ties to our infra.