- OS X 10.8 or later
- Mac which supports Bluetooth Low Energy: 2011 MacBook Air or later, 2012 MacBook Pro or later, 2012 iMac or later, 2011 Mac mini or later, or 2013 Mac Pro
- Knock for iPhone $3.99 on the iTunes Store
- iPhone (4S, 5, 5C, or 5S) running iOS 7 or later