Your event-driven architecture needs a card catalog

What it does

EventCatalog is a documentation and governance platform for event-driven systems. It lets you catalog domains, services, events, and schemas—OpenAPI, AsyncAPI, Protobuf, Avro, JSON Schema—in one searchable place. The project ships as an Astro and React application with an embedded visualizer, AI chat, and an MCP server so both humans and tools can query the architecture.

The interesting bit

Instead of treating documentation as a static wiki, EventCatalog turns it into an explorable graph. You can trace schema fields across services, attach architecture decision records and runbooks directly to resources, and auto-generate entries from Kafka, EventBridge, RabbitMQ, and other sources using its 15-plus generators. It also versions events and commands with full semantic versioning, which is the kind of rigor usually reserved for APIs, not messages.

Key highlights

• Built-in AI chat and MCP server for natural-language architecture queries
• Schema explorer and field-level filtering across OpenAPI, AsyncAPI, Protobuf, Avro, and JSON Schema
• 15-plus generators to ingest specs from AsyncAPI, OpenAPI, Kafka, Confluent, AWS EventBridge, and others
• Semantic versioning for events, commands, services, and domains
• Enterprise features including OAuth2, RBAC, schema governance, and breaking-change detection

Verdict

Worth evaluating if you run a nontrivial event-driven system and are tired of answering “what schema does this topic use?” in Slack. Probably overkill for a single-service app with three events.