PIN Keeper Credit Cards is an Android application developed by Hippo that securely stores your PIN numbers. The app features a 4x4 pattern key and strong encryption using AES (Advanced Encryption Standard), ensuring that your data is protected. The app also has secure memory protection at runtime, partial data storage, and open source code.

With up to 5 free storage slots, PIN Keeper Credit Cards has no ads or usage limitations. However, users can upgrade to premium features, which include cross-platform device synchronization, up to 31 slots storage, changing pattern key, and safe deleting data.

It is important to note that users must enable application data sync for their Google account. Overall, PIN Keeper Credit Cards is a reliable and secure solution for storing your PIN numbers.