Live Helper Chat has desktop client compatible with

• Linux
• Windows
• MacOS

Read more to download it.

Electron desktop app:
https://github.com/LiveHelperChat/electron/releases

Windows client:
Download

MacOS client:
Download

Linux:
https://github.com/LiveHelperChat/livehelperchat/tree/master/lhc_dc_src - You will have to download source code and compile it. QT 4.x is required.