Five App was developed by a Polish entrepreneur Mateusz Mach who was 18 at the time the app launched in 2016. It's also a messenger – but unlike others it allows you to message in American sign language. It's been advertised as great for those learning the language – you can search signs by category or by the first letter of the word, and the sign archive is constantly updated. The signs are animated by tiny avatars, and to make it more fun you can even select the facial expressions they have when they gesture the sign. It also allows you to use text when needed, and the app is integrated with Facebook, so you can send your sign language animations through Messenger.