Schema validation usually happens at the producer client — but what about legacy producers you can't modify, third-party integrations, or teams that simply skip validation? Those schema-invalid messages still reach Kafka, and by the time a consumer fails on bad data, the damage is done and the offset has moved.

In this session, I'll demo a different approach: enforcing schema validation transparently at the proxy layer using Kroxylicious. A proxy filter intercepts produce requests, validates payloads against a schema registry, and rejects non-compliant messages before they ever reach the broker — with zero changes to producer code. I'll show the setup end to end: deploying the proxy alongside a Kafka cluster on Kubernetes, configuring validation rules, and watching bad messages get rejected in real time.

Attendees will leave with:
- An understanding of Kafka proxy-layer architecture and how Kroxylicious filters work
- A deployable schema validation filter configuration for their own clusters
- A clear decision framework for when proxy-layer validation complements or replaces client-side checks