# Creating an event schema in Amazon EventBridge
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You create schemas by using JSON files with either the [OpenAPI Specification](https://swagger.io/specification/) or the [JSONSchema Draft4 specification](https://json-schema.org/specification-links.html#draft-4). You can create or upload your own schemas in EventBridge by using a template or generating a schema based on the JSON of an [event](eb-events.md). You can also infer the schema from events on an [event bus](eb-event-bus.md). To create a schema by using the EventBridge Schema Registry API, use the [https://docs.amazonaws.cn/eventbridge/latest/schema-reference/v1-registries-name-registryname-schemas-name-schemaname.html#v1-registries-nam](https://docs.amazonaws.cn/eventbridge/latest/schema-reference/v1-registries-name-registryname-schemas-name-schemaname.html#v1-registries-nam) API action.

When you choose between OpenAPI 3 and JSONSchema Draft4 formats, consider the following differences:
+ JSONSchema format supports additional keywords that aren't supported in OpenAPI, such as `$schema, additionalItems`.
+ There are minor differences in how keywords are handled, such as `type` and `format`.
+ OpenAPI doesn't support JSONSchema Hyper-Schema hyperlinks in JSON documents.
+ Tools for OpenAPI tend to focus on build-time, whereas tools for JSONSchema tend to focus on run-time operations, such as client tools for schema validation.

We recommend using JSONSchema format to implement client-side validation so that events sent to EventBridge conform to the schema. You can use JSONSchema to define a contract for valid JSON documents, and then use a [JSON schema validator](https://json-schema.org/tools) before sending the associated events.

After you have a new schema, you can download [code bindings](eb-schema-code-bindings.md) to help create applications for events with that schema.