A free program for Android, by Callicia.
BirdieSync is a synchronization application for the contacts and calendars of two Android devices, and it is completely free. This tool allows you to keep your address book and phonebook in sync, regardless of the type of phone you use: it can be a mobile or a tablet. It is the perfect app for people who have an Android tablet and want to sync the information on it with the contacts on their Android phone, and vice versa.
To use it, you need to install it on the device you want to synchronize, and then you will see an icon on the notification bar, indicating that the app is active and that you can use it. The first time you run the app, it will ask you to grant it permissions to access the contacts and calendars. This is a secure way to keep your contacts and events private, as the data is transferred directly from the device to the PC.
It is also possible to use the app to sync the information between two devices that are not connected to the Internet, as long as you have an internet connection on the second device.