Knock

$2.99 FROM Knock Software, knocktounlock. com NEEDS iOS 7 or later

Fancy a different approach to Unlox? Knock lets you – you guessed it – knock on your device to unlock your Mac. Two quick taps on your iPhone or a single tap on your Watch and you’re in.

You don’t even need to open the app, and you can remotely disable it if you lose your device.