Tarantool is an open source NoSQL solution that combines database and cache into one entity and provides APIs for writing application logic in Lua. Both in-memory and disk-based engines are supported, and users can create multiple indexes (HASH, TREE, RTREE, BITSET) based on their use cases. The data itself is stored in MessagePack format and uses the same protocol to communicate between clients and server. Tarantool supports write-ahead logs, transactions and asynchronous master-master replication. We are happy with the architectural decision of embracing single-writer policy and cooperative multitasking to handle concurrent connections.