Scalar DB Is a universal transaction manager for non-transactional and/or heterogeneous databases. It achieves database and storage-agnostic ACID transactions when the underlying database or storage engine is not ACID compliant or in the presence of multiple different databases. In addition, it can be used as a database abstraction that enables database migration without modifying the application. ScalarDB, which is designed to guarantee snapshot isolation and strict serializability, uses a client-coordinated protocol, Consensus Commit, based on Optimistic Concurrency Control, and a multi-dimensional map based on the key-value data model.