---
title: EventModelers.ai
description: What EventModelers.ai is, how its Build Kits turn a slice marked Planned into a tested Cratis vertical slice, and where to find the C#, Kotlin, and Java kits.
slug: eventmodelers-ai
---

import { CardGrid, Aside } from '@astrojs/starlight/components';
import SimpleCard from '@components/SimpleCard.astro';
import TopicHero from '@components/TopicHero.astro';

<TopicHero icon="list-format" eyebrow="The Cratis Stack" title="From a modeled slice to running Cratis code">
[EventModelers.ai](https://eventmodelers.ai) is a visual [event modeling](/event-modeling/) platform where business, engineering, and AI agents design a system on one shared timeline — and mark a slice `Planned` to have an AI coding agent implement it. The **Cratis Build Kits** are the language-specific agents that pick those slices up and turn them into real Cratis (Arc + Chronicle) vertical slices, built, tested, and committed.
</TopicHero>

## What EventModelers.ai is

Requirements written as tickets lose the reasoning behind them the moment they're written down, and an AI coding agent handed a vague ticket guesses — confidently, and often wrong. [EventModelers.ai](https://eventmodelers.ai) closes that gap by making the **event model itself** the shared artifact: a visual timeline of screens, commands, events, and read models that business and engineering read the same way, and that's precise enough for an AI agent to build from directly.

The platform's own loop:

1. **Discover & model** — map commands, events, and read models onto a shared timeline, in a workshop or an AI-assisted session.
2. **Slice the work** — break the model into vertical slices, each a self-contained, buildable unit of business value.
3. **Generate & build** — mark a slice `Planned` on the board; an AI coding agent implements it, runs the tests, and commits.
4. **Stay in sync** — change the model and the code catches up, so the board and the codebase never drift apart.

This is the same vocabulary [Event Modeling](/event-modeling/) already uses in the rest of the Cratis documentation — commands, events, read models, processors — because EventModelers.ai's slice types map directly onto Cratis's own vertical-slice patterns (State Change, State View, Automation, Translation).

<Aside type="note" title="Not a Cratis product">
EventModelers.ai is built by [Nebulit](https://github.com/Nebulit-GmbH), independent of Cratis. The **Build Kits** below are what Cratis maintains: the language-specific agents that consume an EventModelers.ai board and generate Cratis code from it. See [eventmodelers.ai](https://eventmodelers.ai) for the platform itself — workshops, pricing, and the modeling UI live there, not here.
</Aside>

## What a Build Kit does

Each Build Kit is a real-time Claude agent you install into a Cratis project. Once connected to a board, it runs a loop that:

1. **Connects** to the Eventmodelers Platform in real time
2. **Fetches** a slice's definition the moment it's marked `Planned`
3. **Routes** it to the right build skill by slice type — a command/event pair, a projection/read model, or a reactor
4. **Generates** the vertical slice following Cratis conventions for that language
5. **Builds and tests** it, then **updates the board to `Done`**

All without you opening an editor. See [The Loop and Triggers](#pick-your-language) in each kit's documentation for the exact mechanics, and [Event Modeling](/event-modeling/) for why the four slice types map onto Cratis so directly.

## Pick your language

Three Build Kits exist today, one per Cratis client stack. Each is a separate, independently versioned repository — pick the one that matches your project:

<CardGrid>
  <SimpleCard title="C#" icon="code-branch" link="/eventmodelers-ai/csharp/">
    For .NET projects on Cratis Arc + Chronicle.
  </SimpleCard>
  <SimpleCard title="Kotlin" icon="code-branch" link="/eventmodelers-ai/kotlin/">
    For Kotlin projects on Arc.Kotlin + Chronicle.Kotlin.
  </SimpleCard>
  <SimpleCard title="Java" icon="code-branch" link="/eventmodelers-ai/java/">
    For Java projects on Arc.Kotlin + Chronicle.Kotlin.
  </SimpleCard>
</CardGrid>

Every kit follows the same install → connect → run shape:

1. **Install** — `npx github:Cratis/Eventmodelers-Build-Kit-<language> install` scaffolds a Cratis starter app and the agent loop into your project.
2. **Connect a board** — give the kit your EventModelers.ai organization, board, and API token (from [app.eventmodelers.ai/account](https://app.eventmodelers.ai/account)).
3. **Run the loop** — `node .build-kit/ralph-claude.js`, then mark a slice `Planned` on your board and watch it land as tested code.

## See also

- [Event Modeling](/event-modeling/) — the notation and the four slice patterns the kits generate from
- [eventmodelers.ai](https://eventmodelers.ai) — the platform: workshops, the modeling UI, and the [FAQ](https://eventmodelers.ai/docs/eventmodeling-faq)
- [Build a full-stack feature](/build-a-full-app/) — the same command/event/read-model shapes, built by hand