Free refills

eventsourcing

Event sourcing for TypeScript, built on Effect. It is for teams already writing Effect who want an event store, aggregates and projections without learning a second framework.

~$ npm install @codeforbreakfast/eventsourcing-store

On GitHub Get started ↓

What's in the pan

A full English of packages. Order only what you'll eat.

Effect all the way down
Stream · Layer · Schema

Events are Schema types, event streams are Effect Streams, and every service comes in as a Layer. There are no proprietary APIs to learn: if you know Effect, you already know how to use it.
An event store for every sitting
Postgres, memory or disk

PostgreSQL for production, with SQL migrations and LISTEN/NOTIFY for live event streams. An in-memory store for development and tests. A filesystem store that keeps each stream as human-readable JSON, for learning and debugging.
Aggregates and commands
the write side

Aggregate roots for domain-driven design. A command takes domain values and returns the events it decides on, so business rules stay clear of infrastructure. Commands are validated with Effect Schema.
Projections
the read side

Read models built from event streams, kept apart from the write side in proper CQRS fashion.
Served hot over WebSockets
optional side

Transport and protocol layers stream events to clients in real time. A REST API can skip them and talk to the aggregates directly.
Checked at the pass
test suites included

Standard test suites that check an event store or transport behaves as the contract says, so an implementation of your own can prove it does too.

How to order

Effect is the one side you can't leave off the plate.

You need TypeScript 5 and Effect 3, which every package takes as a peer dependency. Every package is still below 1.0, so its API may move before it settles. It is MIT licensed.

npm install effect \
  @codeforbreakfast/eventsourcing-store \
  @codeforbreakfast/eventsourcing-store-inmemory \
  @codeforbreakfast/eventsourcing-aggregates \
  @codeforbreakfast/eventsourcing-projections

The usage guide walks from your first event to an aggregate. The todo app example is a whole application with aggregates, projections and a process manager. Each package's README is in the repository.

Cooked in the same kitchen

Code For Breakfast built this. It cooks for clients too.

Code For Breakfast Ltd is a UK software consultancy, based in Reading and working remote-first. The kitchen that made this ships well-tested software for clients, fast, and builds and operates real multi-agent AI systems.

See what's on the menu Book a table

eventsourcing

Effect all the way down

An event store for every sitting

Aggregates and commands

Projections

Served hot over WebSockets

Checked at the pass