Hello Edgar,
The comparability matrix was only added to the docs for 4.0 release
(something way overdue...), as 4.0 contains major changes.
I assume you are talking about broker version 3.9.1. For this case, all
clients, even back to 0.x, and also all newer clients are supported.
There might be some broker features, that older clients cannot use of
course, as older client got developed before these newer broker features
got added, but 3.9.1 brokers are fully backward compatible to older clients.
Apache Kafka 4.0.0 is the first release, which drop supports for older
clients, and the minimum supported client version is 2.1 now.
This KIP might help:
https://cwiki.apache.org/confluence/display/KAFKA/KIP-1124%3A+Providing+a+clear+Kafka+Client+upgrade+path+for+4.x
Please let us know if you have any more specific follow up questions.
-Matthias
On 10/2/25 11:23 PM, Zubel, Edgar wrote:
Hello!
I was looking for kafka-client and kafka-broker API version compatibility
matrix and unfortunately didn’t find that information anywhere.
Kafka 4.0.0 has some sort of compatibility matrix provided in the
documentation, but I’m interested in version 3.9.1.
Is there a way to find that out?
My assumption here would be, that broker provided API version support –
SupportedMinVersion: 3.0-IV1 SupportedMaxVersion: 3.9-IV0 , would mean, that
clients from version 3.0.X to 3.9.X are supported?
Please help me out here.
Thanks!
Best regards,
Edgar Zubel
DevOps Engineer
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