Seems more like an inetd to me. Give a command and run it again and again.

It's similar to netcat -e and inetd, except it also handles the WebSocket protocol (negotiating the handshake and message framing), so your apps don't need to.

If you're on Ubuntu (and maybe other distros as well), be sure to install the nc-traditional package. Otherwise you don't get the nifty features such as -e

Basically, but it also handles some details specific to the websockets protocol.