Open-source product · MIT license
The event database for decisions that must stay correct.
Orisun is an event sourcing database built in Go. It gives high-consequence systems a complete, verifiable history of every fact — and stops a write the moment the facts behind a decision have changed.
Capabilities
An event store built for production truth.
Most databases tell you what is true now. Orisun keeps the full sequence of facts that made it true — and enforces that writes are made against the same facts the decision was based on.
Command Context Consistency
Every write declares the facts it relied on. If those facts have changed, Orisun rejects the write instead of silently corrupting the decision — optimistic concurrency expressed as business intent, not version numbers.
Complete, verifiable history
Domain events are immutable and append-only. Auditors, regulators, and future features all read from the same durable record of what actually happened, in order.
Embedded subscriptions
Projections and read models subscribe through embedded NATS JetStream — no separate broker to deploy for event notifications and view-state updates.
gRPC APIs and official clients
A compact gRPC contract with maintained clients for Go, Java, and Node.js, so teams integrate without adopting our stack.
Your storage backend
Run Orisun on PostgreSQL, YugabyteDB, SQLite, or FoundationDB. Start embedded in a single binary, scale to a distributed cluster — the event contract stays the same.
Open source, MIT licensed
No open-core fence, no feature ransom. Inspect the code, run it anywhere, and build commercial systems on it without asking us.
Proven in production
The database underneath our own products.
Orisun is not a side project. It is the foundation of Ìpìlẹ̀, our event-sourced core banking platform, and of Frases, a consumer language-learning product shipped to the App Store for a client.
Event sourcing earns its complexity where decisions must stay correct as facts change: ledgers, payments, approvals, inventory, policy. If a wrong write is expensive in your domain, Orisun was built for you.
Work with us
Ready to build from the source?
Bring us the product that needs to scale, the workflow holding your team back, or the decision your data cannot yet support.