Mumble - Mumble is an open source, low-latency, high quality voice chat software primarily intended for use...
itch.io - An online game marketplace and community.
Discord - Step up your game with a modern voice & text chat app. Crystal clear voice, multiple server and channel support, mobile apps, and more.
GOG.com - DRM-free game store, selling both new and old titles. No clients required.
GSC - With GSC, you can pick from any of 14 worldwide datacenters to host your own free voice server.
GnuPlot - Gnuplot is a portable command-line driven interactive data and function plotting utility.