Is the Confluent Platform based on Kafka free? open source?
Kafka itself is completely free and open source.
Confluent is the for profit company by the creators of Kafka. The Confluent Platform is Kafka plus various extras such as the schema registry and database connectors. I presume Confluent makes money by selling support contracts and services.
Is the Confluent Platform free and/or open source? Am I obligated to purchase licensing or paid support?
Answer
The Confluent Platform is free and open source (see https://github.com/confluentinc/ for the source).
There is also a Confluent Platform Enterprise version that includes the Control Center monitoring app (which is not open source) and includes support for the core Kafka, Confluent Platform OS components, and Control Center.
See http://www.confluent.io/product for more details.
UPDATE for Version 5.1 and above
On Dec 14th, 2018 Confluent announced that that new versions of the Confluent Platform (starting with Version 5.1) will be distributed under a new Confluent Community License.
The detailed FAQ about the new license located at https://www.confluent.io/confluent-community-license-faq includes the following question and answer:
“Is Confluent Community License open source?
Strictly speaking it is “source-available.” Many people use the phrase “open source” in a loose sense to mean that you can freely download, modify, and redistribute the code, and those things are all true of the code under the Confluent Community License. However, in the strictest sense “open source” means a license approved by the Open Source Initiative (“OSI”) which meets a particular set of criteria. The Confluent Community License is not approved by the OSI and likely would not be as it excludes the use case of creating a SaaS offering of the code. Because of this, we will not refer to the Confluent Community License or any code released under it as open source.”
Announcement of License changes: https://www.confluent.io/blog/license-changes-confluent-platform
The actual Confluent Community License https://www.confluent.io/confluent-community-license