Download one of these from the download page, then run the matching line in a terminal, in the folder you downloaded to (the file names have the version in them):
AppImage
chmod +x Pendling_*_amd64.AppImage && ./Pendling_*_amd64.AppImageDebian, Ubuntu
sudo apt install ./Pendling_*_amd64.debFedora, openSUSE
sudo dnf install ./Pendling-*.x86_64.rpmThe charm hangs from the top of your screen, and its icon appears in the tray.
No tray icon on GNOME?
GNOME hides tray icons unless you add the AppIndicator and KStatusNotifierItem Support extension. (Ubuntu has it already.)
Updates
When there's a new version, the charm tells you, and one click installs it. Every update is signed, and checked before it installs. You can also choose Check for Updates… in the tray menu.
Uninstall
Delete the AppImage, or sudo apt remove pendling / sudo dnf remove pendling. Your settings are in ~/.local/share/com.karthikanbarasan.pendling.