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The stream database built for Event Sourcing

EventStoreDB is an industrial-strength database technology used as the central data store for event-sourced systems. It is available open-source to run locally on most platforms or as SaaS through Event Store Cloud.

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Why use EventStoreDB?

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.

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  • Audit icon

    Audit

    EventStoreDB stores your data as a series of immutable events over time, providing one of the strongest audit log options available (characteristics similar to a blockchain)

  • Root Cause Analysis icon

    Root cause analysis

    Business events can be tied back to originating events providing traceability and visibility of entire workflows from start to finish

  • Event-driven Architecture icon

    Event-driven architecture

    Unlike traditional databases which optimize pooling data into opaque silos, event streams can be listened to, allowing businesses to react in real-time to events

  • Service Autonomy icon

    Service autonomy

    If a service goes down dependent services can “catch up” when the source comes back up. Because events are stored in a sequence in the stream, knowing the current position allows synchronization

  • Replay and Reshape icon

    Replay and reshape

    The series of changes (events) in a stream can be replayed and transformed as new business requirements inevitably emerge, e.g. the event stream can be replayed to a point in time and “what if” analysis can be used to project potential future outcomes

  • Legacy Migration icon

    Legacy migration

    The migration of legacy systems to modern distributed architectures can be carried out in an incremental manner, gradually replacing specific pieces of functionality with event-sourced services (strangler pattern). Existing read paths of the legacy system can remain in place while writes are directed to the services

  • Asynchronous First icon

    Asynchronous first

    Event sourced systems strive for the minimum amount of synchronous interaction, consistency boundaries are consciously chosen so that business requirements are met and everything else is eventually consistent. This results in responsive, high performance, scalable systems

  • Occasionally Connected icon

    Occasionally connected

    Since there is a log of all state changes of an application, it can be used in occasionally connected system scenarios. When a device is disconnected it can continue to work on its own data locally and synchronize upon connection

  • Observability icon

    Observability

    In event-sourced systems, events flow through queues and streams increasing observability - what is uniquely powerful is that the events can contain the business context which allows real-time observations and analytics

  • One Way Data Flow icon

    One way data flow

    Data in a CQRS/event-sourced system flows one way (through independent models to update or read information), this brings an improved ability to reason about data and debug as each component in the data flow has a single responsibility

What is Event Sourcing?

Event Sourcing is an alternative way to persist data in which all changes in a system are stored as an immutable series of events in the order that they occurred. The current state is derived from that event log.

This contrasts with state-oriented persistence that only keeps the latest version of the entity state; when changes occur in "traditional" database systems, the state is updated and the history, along with the reason for the change, is lost.

In event-sourced systems, whenever an action occurs that changes the state of a business entity (for example an order is marked as shipped), the system will publish an event to the stream describing what has happened (as per the example, the event might be OrderShipped). In EventStoreDB, additional metadata can also be stored in each event such as a timestamp, what action caused the event, and who performed that action.

The stream (or streams: EventStoreDB allows you to define and create many streams as required for your domain model) comprises a log of all events that have occurred, and by replaying them the current state can be derived. That can output the same end-result as in a traditional database, but it can also provide much more; you can perform additional tasks such as time travelling through the system and root cause analysis. And being immutable it provides one of the strongest methods for audit log available.

Read our beginner's guide to Event Sourcing

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Main features

EventStoreDB's core database server is used in production systems worldwide. The core features make it the ideal database choice for building event-sourced systems. It’s available as open-source software so it’s free to use. And with our tutorials it’s easy to get started: you’ll have a demo application to write and read events in minutes.

  • Guaranteed writes
  • Multiple client interfaces
  • Great performance that scales
  • Immutable data store
  • High availability
  • Optimistic concurrency checks
  • Multiple hosting options
  • Atom subscriptions
  • Projections
  • Subscribe to streams with competing consumers
  • Commercial support plans
More about EventStoreDB

Who's using Event Store?

One of the incredible benefits of Event Sourcing is the ability to unlock conversations, ideas, and research by examining the complete picture.
Aaron Hanna, Chief Architect at Insureon
Jet Checkout.com PWC CERN Xero NHS Digital Arnold Clark logo-linedata Bergen Kommune Made.com Skyguide UK Hydrographic Office
View our case studies

Learn EventStoreDB

It’s easy to get started with EventStoreDB.

If you are a new user, follow our getting started guide for step-by-step instructions on downloading and installing EventStoreDB, and writing sample applications to write and read events.

If you know the basics but want to know more, check out our tutorials for in-depth guides on specific features or use cases of EventStoreDB, our docs section for technical documentation, or head over to the community forum where we have an active community of users.

Getting started guideTutorials

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