# Event enrichment in Amazon EventBridge Pipes
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With the enrichment step of EventBridge Pipes, you can enhance the data from the source before sending it to the target. For example, you might receive *Ticket created* events that don’t include the full ticket data. Using enrichment, you can have a Lambda function call the `get-ticket` API for the full ticket details. Pipes can then send that information to a [target](eb-pipes-event-target.md).

You can configure the following enrichments when setting up a pipe in EventBridge:
+ API destination
+ Amazon API Gateway
+ Lambda function
+ Step Functions state machine
**Note**  
EventBridge Pipes only supports [Express workflows](https://docs.amazonaws.cn/step-functions/latest/dg/concepts-standard-vs-express.html) as enrichments.

EventBridge invokes enrichments synchronously because it must wait for a response from the enrichment before invoking the target.

Enrichment responses are limited to a maximum size of 6MB.

You can also transform the data you receive from the source before sending it for enhancement. For more information, see [Amazon EventBridge Pipes input transformation](eb-pipes-input-transformation.md).

## Filtering events using enrichment
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EventBridge Pipes passes the enrichment responses directly to the configured target. This includes array responses for targets that support batches. For more information about batch behavior, see [Amazon EventBridge Pipes batching and concurrency](eb-pipes-batching-concurrency.md). You can also use your enrichment as a filter and pass fewer events than were received from the source. If you don’t want to invoke the target, return an empty response, such as `""`, `{}`, or `[]`.

**Note**  
If you want to invoke the target with an empty payload, return an array with empty JSON `[{}]`.

## Invoking enrichments
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EventBridge invokes enrichments synchronously (invocation type set to `REQUEST_RESPONSE`) because it must wait for a response from the enrichment before invoking the target.

**Note**  
For Step Functions state machines, EventBridge only supports [Express workflows](https://docs.amazonaws.cn/step-functions/latest/dg/concepts-standard-vs-express.html) as enrichments, because they can be invoked synchronously.