OZO is a C++17 library for asyncronous communication with PostgreSQL DBMS. The library leverages the power of template metaprogramming, providing convenient mapping from C++ types to SQL along with rich query building possibilities. OZO supports different concurrency paradigms (callbacks, futures, coroutines), using Boost.Asio under the hood. Low-level communication with PostgreSQL server is done via libpq. All concepts in the library are designed to be easily extendable (even replaceable) by the user to simplify adaptation to specific project requirements. The library is header-only, but if you want to build and run unit-tests you can do it as listed below.