What Are Kafka Record Headers? Every Kafka record carries a list of Header objects — key-value pairs of String key and byte[] value. They sit outside the message payload and are ideal for: Trace propagation — carry X-Trace-Id / X-Span-Id across service boundaries Correlation IDs — link a response to a request in async flows Routing metadata — signal which region, tenant, or feature flag applies Schema type hints — __TypeId__ (set automatically by JsonSerializer) Event versioning — indicate schema version without modifying the payload flowchart LR subgraph Record["