Google Calendar / Google Calendar - we have to admit that this is probably one of the best calendars you've ever seen. Its main feature not in terms of what functions it contains, and not in its interface, although it is made pretty well. The main feature of this app is its developer. Google can boast a whole bunch of technological innovations. And their calendar will delight you with the fact that tied to your account and affects other applications such as notes and more, thus you use a system of applications interacting with each other.