TripMode $7.99 (approx £6.20)

tripmode.ch

Concerned that iCloud Drive, say, may be sending or receiving a lot of data in the background while your Mac is connected to Personal Hotspot on your iPhone? Or, that you forget about such cost concerns when using ordinary apps? Click TripMode’s menu bar icon to see apps and services that use a network connection. Switch it on and tick the checkbox next to only those items you want to have internet access; the icon then turns red as a reminder some things are blocked.