MeshCentral for providing remote IT support. I run it in a lightweight VM on very modest hardware (ancient Core 2 system I had kicking around) and it works great. The sheer breadth of features is damn impressive and I’d consider it among some of the best open source projects in terms of UI. No middleman like TeamViewer or Splashtop, and it only costs me a bit of time and hardware.
Updoot for MeshCentral. I can’t believe how excellent and capable this free software is.