eHarmony uses MongoDB to make it easier for couples to find each other. At the forefront of big data and machine learning, eHarmony’s matching system uses a flow algorithm to process a billion potential matches per day. The Compatibility Matching System® uses bi-directional, user-defined criteria to match members based on a comprehensive set of traits and preferences. The system was originally built on a relational database, but with over 51MM+ users, it took more than 2 weeks for the matching algorithm to run. By switching to MongoDB, eHarmony reduced the time to match by 95% to under 12 hours. Learn about eHarmony's matching system, its technology evaluation process, and how it has used MongoDB to make the happiest couples in the world.