Can BusyCal show the Alarm window on all monitors or desktop spaces?

BusyCal can make its Alarm window available across all macOS Desktop Spaces.

To enable this, go to BusyCal > Settings > Alarms, make sure Show alarms is checked, select Use BusyCal Alarm Window, then enable Show in all desktop spaces.

This helps when you use Mission Control, multiple Desktops/Spaces, full-screen apps, or multiple monitors with separate Spaces. The Alarm window is allowed to appear across Spaces instead of being tied to only the desktop where it first opened.

This setting does not create a separate duplicate Alarm window on every physical monitor at the same time. macOS still manages the Alarm window as one window. If you are asking for the alarm to be mirrored simultaneously on every monitor, that is different from Show in all desktop spaces.

For more Alarm window options, see Alarms and Alarms Settings.