BCCAPI

The BCCAPI (Bitcoin Client API) is a java library designed for making secure light-weight bitcoin clients. The BCCAPI connects to a server that holds the block chain, and which tracks the client’s wallet balance. The server only has knowledge of the clients public keys, and is in no position to spend funds owned by the client’s wallet.

Features include:

• Deterministic private keys, based on seed file.
• Only the seed file needs to get backed up, or generated from a passphrase.
• Send/receive Bitcoins
• Low bandwidth
• Low CPU usage
• Server does not have your private keys and is in no position to spend your coins
• Allows spending of unconfirmed-change-sent-back-to-self like the Satoshi Client
• Open source
• Free service, running on donations

Simply put the API is designed for making it easy to create light-weight secure Bitcoin wallets for handheld devices. BitcoinSpinner is an Android app implemented on top of the BCCAPI and available on the Android Market.

The sources include a very simple console based client, that shows how to use it.

The donation address for BCCAPI is 143SikKpjzwhBy5Z7Qg5knu5nKXWExSqQi

The server is closed-source. Jan Moller said "The server side is however not as clean and well documented as the client side, and I am not ready to make the server side open source. At least not yet."