EventStoreDB
The stream database optimised for event sourcing
...Available for free download on most platforms or use our managed service Event Store Cloud. EventStoreDB is an open-source database technology that stores your critical data in streams of immutable events. It was built from the ground up for Event Sourcing, we believe that makes it the best solution in the market for building event-sourced systems. Event Sourcing offers some great benefits over state-oriented systems; the key ones are explained below. An event-sourced system stores your data as a series of immutable events over time, providing one of the strongest audit log options available. ...