kafkacat

Kafkacat, now commonly referred to as kcat, is a lightweight command-line client for Apache Kafka. It provides both producer and consumer functionality and is built on top of librdkafka, the C/C++ Kafka client library. Developed by Edenhill, kafkacat is designed for quick testing, debugging, and scripting interactions with Kafka clusters.

The tool operates in two main modes: producer mode (-P) sends messages to a topic from standard input or a file; consumer mode (-C) reads messages from a topic and prints them to standard output. It supports a range of options to control behavior, including specifying bootstrap servers (-b), topic (-t), and starting offset (-o) such as beginning or end. End-of-partition handling can be managed with -e. Output formatting can be customized with -f and a key delimiter with -K. Configuration options can be supplied with -X, and consumer-group consumption can be performed with -G to specify a group.

Kafkacat is built on librdkafka, which provides access to Kafka features such as partitions, offsets, topics, and metadata. It is cross-platform within UNIX-like systems and Windows and is widely used for ad-hoc interactions, broker connectivity testing, producing seed data, inspecting topic content and offsets, and for scripting in batch processes.

In most distributions and repositories, the tool is now marketed under the name kcat, with kafkacat remaining widely recognized in historical references. The two names refer to the same utility, with kcat representing the contemporary canonical name in recent releases.

See also: Apache Kafka, librdkafka, kcat.