Freedom251 › Streaming Analytics Software

Apache Flink

Free plan APILinuxSelf-hosted

What Apache Flink is

Apache Flink is a framework and distributed processing engine for stateful computations over bounded and unbounded data streams. It supports event-driven applications, stream and batch analytics, and data pipelines and ETL. Listed capabilities include exactly-once state consistency, event-time processing, and handling for late data. Its APIs include SQL for stream and batch data, the DataStream API, and ProcessFunction for time and state. Operational options include flexible deployment, high availability, savepoints, scale-out architecture, support for very large state, and incremental checkpoints. The project also lists low latency, high throughput, and in-memory computing. Flink is self-hosted and free under Apache License v2, and is designed for common cluster environments; the Kubernetes Operator is identified as the standard way to deploy it on Kubernetes. Separately released connectors include options for AWS, Cassandra, Elasticsearch, Kafka, MongoDB, and others. Security configuration matters: authentication and SSL/TLS are disabled by default, and submitted code runs with the operating system permissions available to it.

Who it suits

Flink suits teams building event-driven applications, stream or batch analytics, and data pipelines or ETL who can operate a self-hosted system. Production and shared deployments need careful security configuration.

What it does well

Supports stateful processing of bounded and unbounded streams.
Offers SQL, DataStream, and ProcessFunction APIs.
Lists high availability and incremental checkpoints.
Free under Apache License v2.
Supports Java, Python, and Scala.

What to know first

Self-hosted deployment requires operational responsibility.
SSL/TLS and listed authentication options are disabled by default.
Submitted code is not sandboxed.
Mailing-list posting requires subscription.

Limits

Flink is free under Apache License v2, and no free-plan quota is stated. For production or shared deployments, SSL/TLS and REST API and SQL Gateway authentication must be configured because they are disabled by default.

Plans

Plan	Billed and limits	Price
Apache Flink	Open source under Apache License v2	Free

As flink.apache.org lists them, read 30 Sept 2026. The maker's own page has the final word.

Getting started

Visit https://flink.apache.org/ and review the project’s deployment information.
Choose a common cluster environment for a self-hosted deployment.
For Kubernetes, use the Kubernetes Operator as the standard deployment mechanism.
Select the listed APIs and separately released connectors needed for your application.
Configure SSL/TLS and REST API or SQL Gateway authentication for production or shared deployments.

Verdict

Apache Flink offers stream and batch processing APIs with operational capabilities for self-hosted deployments. Its security defaults and code execution permissions make deployment configuration an important consideration.

Questions

How much does Apache Flink cost?

The listed plan is free, under Apache License v2.

Is Apache Flink open source?

The plan describes it as open source under Apache License v2.

Where can Apache Flink run?

It is self-hosted and designed for common cluster environments. The project identifies its Kubernetes Operator as the standard deployment mechanism on Kubernetes.

Which programming languages are supported?

The listed languages are Java, Python, and Scala.

What APIs does Flink provide?

Its listed APIs include SQL for stream and batch data, the DataStream API, and ProcessFunction for time and state.

What should operators know about security?

Flink is not a sandbox: submitted code runs with the operating system permissions available to it. SSL/TLS and REST API and SQL Gateway authentication are disabled by default and require configuration for production or shared deployments.

Facts from Apache Flink's own pages

APIs: Its listed layered APIs include SQL on stream and batch data, the DataStream API, and ProcessFunction for time and state. · flink.apache.org, 30 Sept 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, 30 Sept 2026
Correctness: The site lists exactly-once state consistency, event-time processing, and sophisticated late-data handling as capabilities. · flink.apache.org, 30 Sept 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, 30 Sept 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, 30 Sept 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, 30 Sept 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, 30 Sept 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, 30 Sept 2026
Performance: The site lists low latency, high throughput, and in-memory computing as performance capabilities. · flink.apache.org, 30 Sept 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, 30 Sept 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, 30 Sept 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, 30 Sept 2026
Use cases: Flink supports event-driven applications, stream and batch analytics, and data pipelines and ETL. · flink.apache.org, 30 Sept 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, 30 Sept 2026