To test against a real Apache Kafka cluster, developers can use the Confluent CLI to launch Confluent Platform and produce/consume data from Kafka topics. However, generating realistic test data for these topics can be challenging. To overcome this, Confluent provides a Kafka Connect Datagen Connector that allows developers to generate more interesting test data locally. This connector can produce records with complex data types, randomizing the data and customizing the schema as needed. Additionally, developers can use predefined datasets or define their own schema specifications to generate specific data formats such as Avro or JSON. With this tool, developers can exercise their client applications, build demos, troubleshoot issues, or learn more about how Kafka works in a controlled environment.