Answer by Chris Halcrow for Effective strategy to avoid duplicate messages in apache kafka consumer

There's a relatively new 'Transactional API' now in Kafka that can allow you to achieve exactly once processing when processing a stream. With the transactional API, idempotency can be built in, as long as the remainder of your system is designed for idempotency. See https://www.baeldung.com/kafka-exactly-once