The world of databases is no stranger to open source. In fact, many of the world’s top companies, projects, and websites run various open source databases behind the scenes. Because the choice of database has enormous implications for scalability, performance, and how the data itself can be queried, there are numerous options to meet all sorts of potential needs. RethinkDB is an open source database with a specific purpose: serving data to realtime applications, whether those applications are video game backends, financial tools, or analytics suites.