This is a scalable blockchain database. It is not strictly a blockchain itself but complements blockchain technology by providing a decentralized database. At its core it's a distributed database but with the added attributes of a blockchain such as decentralization, immutability, and handling of digital assets. It also allows usage of NoSQL for querying the database.
It is intended to provide a database in a decentralized ecosystem where not only processing is decentralized (blockchain) or the filesystem is decentralized (for example, IPFS) but the database is also decentralized. This makes the whole application ecosystem decentralized.
This is available at https://www.bigchaindb.com/.
