I’m pretty sure Jackdaw doesn’t support KStream-KTable inner joins. (Please correct me if I’m wrong.) So I’ve forked the Jackdaw repo and moved join from IKTable to IKStreamBase, and added join implementations for streams as well as tables. These changes are in the commit at https://github.com/simon-katz/jackdaw/commit/155c5556e2b258f30870036b0ab058389d528f33 I’m new-ish to Kafka and Jackdaw, so I’d appreciate any comments before I turn the commit into a PR.