1. https://sharedrop.io Web-RTC based; Local LAN transfer doesn't leave LAN
2. https://file.pizza HTTP streaming and Web-RTC based.
3. https://ppng.ml HTTP streaming, supporting curl based command line.
Source code at: https://github.com/nwtgck/piping-server, and a minimal golang version at https://github.com/nwtgck/go-piping-server
Blog at https://dev.to/nwtgck
4. https://xkcd949.com HTTP Streaming
WebRTC Demo using peer.js: