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Apache Flink
What it is
Apache Flink is a distributed processing framework for stateful work across bounded and unbounded data streams. It supports event-driven applications, stream and batch analytics, and data pipelines and ETL. Its listed capabilities include exactly-once state consistency, event-time processing, and late-data handling. APIs include SQL for stream and batch data, the DataStream API, and ProcessFunction for time and state. Flink also lists flexible deployment, high availability, savepoints, scale-out architecture, support for very large state, and incremental checkpoints. The project cites low latency, high throughput, and in-memory computing as performance capabilities. It is self-hosted and free under Apache License v2, with Java, Python, and Scala among its supported languages. Separately released connectors cover services and systems including AWS, Kafka, MongoDB, and RabbitMQ. Security configuration requires attention: SSL/TLS, REST API authentication, and SQL Gateway authentication are disabled by default, and submitted code runs with the operating system permissions available to it.
For and against
For
- Free under Apache License v2
- Supports stream and batch SQL
- Lists exactly-once state consistency
- Supports Java, Python, and Scala
- Offers incremental checkpoints
Against
- Self-hosted deployment
- Authentication and SSL/TLS are disabled by default
- Submitted code is not sandboxed
The verdict
Apache Flink combines stream and batch processing APIs with state, event-time, and cluster-operation capabilities. Its security settings and the permissions available to submitted code need consideration before production or shared use.
Who it suits
Flink suits teams building event-driven systems, stream or batch analytics, and data pipelines, especially those able to operate self-hosted cluster deployments. Users sharing deployments should account for its security configuration requirements.
Plans and prices
Apache Flink
Open source under Apache License v2
Read 30 Sep 2026 · flink.apache.org
On the record
- APIs
- Its listed layered APIs include SQL on stream and batch data, the DataStream API, and ProcessFunction for time and state.flink.apache.org · read 30 Sep 2026
- Community support
- The project lists its user mailing list as a support channel and also points users to Slack and Stack Overflow.flink.apache.org · read 30 Sep 2026
- Correctness
- The site lists exactly-once state consistency, event-time processing, and sophisticated late-data handling as capabilities.flink.apache.org · read 30 Sep 2026
- Deployment options
- Flink is designed to run in common cluster environments, and the site identifies the Kubernetes Operator as the standard deployment mechanism for Flink on Kubernetes.flink.apache.org · read 30 Sep 2026
- Integrations
- Separately released connectors listed on the downloads page include AWS, Cassandra, Elasticsearch, Google Cloud PubSub, HBase, Hive, JDBC, Kafka, MongoDB, OpenSearch, Prometheus, Pulsar, and RabbitMQ.flink.apache.org · read 30 Sep 2026
- Known vulnerabilities
- The project does not maintain its own CVE list and directs users to the Apache Security database for Flink CVEs.flink.apache.org · read 30 Sep 2026
- License and maintainer
- The site states that its content is under Apache License v2 and identifies the Apache Software Foundation as the trademark holder.flink.apache.org · read 30 Sep 2026
- Operations
- The site lists flexible deployment, high-availability setup, savepoints, scale-out architecture, support for very large state, and incremental checkpoints.flink.apache.org · read 30 Sep 2026
- Performance
- The site lists low latency, high throughput, and in-memory computing as performance capabilities.flink.apache.org · read 30 Sep 2026
- Security boundary
- Flink trusts the cluster operator and authenticated job submitters; submitted code runs with the operating system permissions available to it, so Flink is not a sandbox.flink.apache.org · read 30 Sep 2026
- Security configuration
- SSL/TLS, REST API authentication, and SQL Gateway authentication are disabled by default and must be configured for production or shared deployments.flink.apache.org · read 30 Sep 2026
- Support limitation
- A user needs to subscribe to a mailing list before posting, and Jira requires an ASF JIRA account to log issues.flink.apache.org · read 30 Sep 2026
- Use cases
- Flink supports event-driven applications, stream and batch analytics, and data pipelines and ETL.flink.apache.org · read 30 Sep 2026
- What it does
- Apache Flink is a framework and distributed processing engine for stateful computations over unbounded and bounded data streams.flink.apache.org · read 30 Sep 2026
