Broncko/ArangoDB
ArangoDB is a universal open-source database with flexible data model for documents, graphs, and key-values. Build high performance application using a convenient sql-like query language or JavaScript/Ruby extensions. It is a durable, reliable, transactional multi-model database. It's key-features are: Schema-free schemata, an integrated application server, flexible data modelling, free index choice, and configurable durability.