Bitcoinj is an open-source Bitcoin client library built using Java and implements the Bitcoin network protocol. With version 0.7, it was renamed from BitCoinJ to bitcoinj.
The project was announced on March 7, 2011. The project was built by Mike Hearn while he was a Google employee as a "20 percent time" project.
- Bitcoin wallet - a standalone wallet for Android and BlackBerry devices
- Hive - a wallet for Mac OS X with an integrated applications platform
- bitcoinj project page on Google Code.