# Getting started with schemas

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EventCatalog supports **any schema or specification format**, including (but not limited to):

* JSON / YAML
* Avro
* Protobuf
* GraphQL
* OpenAPI
* AsyncAPI

Schemas are **optional**, but they add valuable context to your messages and services by making data structures explicit and discoverable.

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## Why add schemas?[​](#why-add-schemas "Direct link to Why add schemas?")

By adding schemas to your messages and services, you unlock several benefits:

* **Schema Explorer** – Quickly find and browse schemas [(see demo)](https://demo.eventcatalog.dev/schemas/explorer)
* **Fields Explorer** – Browse every schema field catalog-wide, search across formats, and trace fields to the services that produce and consume them [(see guide)](/docs/development/guides/schemas/fields-explorer.md)
* **API access** – Access schemas programmatically through the EventCatalog API [(see guide)](/docs/development/guides/schemas/schema-api.md)
* **Ask questions** – Query and explore schemas using the [EventCatalog MCP](/docs/development/ask-your-architecture/mcp-server/introduction.md)
* **Visualization** – Help developers understand data structures using [schema property search and visualization](/docs/development/components/components/schema-viewer.md)
* **Field Usage** – Track which services depend on specific fields to understand the impact of schema changes [(see guide)](/docs/development/guides/schemas/field-usage.md)

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## Adding schemas to messages[​](#adding-schemas-to-messages "Direct link to Adding schemas to messages")

You can attach one or more schemas to any message type:

* **Commands** -
* **Queries**
* **Events**

Get started by following the relevant guide:

* [Adding schemas to commands](/docs/development/guides/messages/common/adding-schemas.md)
* [Adding schemas to queries](/docs/development/guides/messages/common/adding-schemas.md)
* [Adding schemas to events](/docs/development/guides/messages/common/adding-schemas.md)

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## Adding specifications to services[​](#adding-specifications-to-services "Direct link to Adding specifications to services")

In addition to message-level schemas, services can render full API and messaging specifications, including:

* **AsyncAPI**
* **OpenAPI**
* **GraphQL**

Use the guides below to add specifications to your services:

* [Adding AsyncAPI specifications to services](/docs/development/guides/services/adding-to-services/asyncapi.md)
* [Adding OpenAPI specifications to services](/docs/development/guides/services/adding-to-services/openapi.md)
* [Adding GraphQL schemas to services](/docs/development/guides/services/adding-to-services/graphql.md)