Cachebox is the geocaching program.
It is open source, mainly on github and sourceforge and is created by volunteers.

Cachebox runs on smartphones with Android short ACB (Cachebox version 2).

If you still have a Windows Mobile or PDA, you can also use the original version, CB for short (Cachebox version 1).

On a Windows PC, a centralized database managed by WCB supports the mobile devices and Web server CBS, which provides ACB with data and retransfers changes to the central database on the go. With DCB the possibility is created to work with Linux-like systems.
With the development of ACB in version 3, short ACB3, the program should also run on ios.

All programs use an identically structured database via SQLite (*.db3). On Windows systems, Cachebox version 1 can also use the SQL Server Compact Edition (*.sdf). WCB can handle both types of databases.

Who lands on this website, has probably installed Cachebox from the Google Playstore. In the Geoclub Forum users and developers are on hand to help and advise. The programs all have certification as Groundspeak Authorized Developer for Geocaching Apps.