Apache Flink vs Apache Kafka

Apache Flink is a free, self-hosted framework and distributed processing engine for stateful computations over unbounded and bounded data streams. It supports event-driven applications, stream and batch analytics, and data pipelines and ETL. Listed correctness features include exactly-once state consistency, event-time processing and late-data handling. APIs include SQL for stream and batch data, DataStream and ProcessFunction for time and state. Operational capabilities cover flexible deployment, high availability, savepoints, scale-out architecture, very large state and incremental checkpoints. The project lists low latency, high throughput and in-memory computing. Flink runs in common cluster environments; for Kubernetes, the Kubernetes Operator is identified as the standard deployment mechanism. Connectors include AWS, Cassandra, Elasticsearch, Google Cloud PubSub, HBase, Hive, JDBC, Kafka, MongoDB, OpenSearch, Prometheus, Pulsar and RabbitMQ. Security requires configuration because SSL/TLS, REST authentication and SQL Gateway authentication are disabled by default. It is available at free under Apache License v2.

Apache Kafka is an open-source distributed event-streaming platform for data pipelines, streaming analytics, data integration, and mission-critical applications. Applications can publish and subscribe to event streams, retain them durably, and process them either in real time or later. Kafka supports durable, fault-tolerant replication across availability zones, data centers, or geographic regions. Kafka Streams provides stateful operations, aggregations, windowing, joins, event-time processing, and exactly-once processing. Kafka Connect links hundreds of event sources and sinks, including Postgres, JMS, Elasticsearch, and AWS S3. Deployments can use bare metal, virtual machines, or containers, on premises or in the cloud, with self-managed or vendor-managed options. The project describes network-limited throughput, latency as low as 2 ms, and clusters of up to 1,000 brokers. Kafka is self-hosted, free, and open source under Apache License 2.0. A local quickstart requires Java 17 or later.