Free and open first
Best Stream Processing Software in 2026
If your software needs to process events as they arrive, compare the listed deployment models, source connectors, and supported languages. Event-time windows and stateful processing describe further aspects to weigh, while SQL processing may be relevant to how you work with stream data. AFL++, Apache Beam, and Apache NiFi are among the entries shown. Free-plan availability and paid-from pricing provide cost context. Consider how each product's stated capabilities fit your data sources, processing requirements, and operating environment.
- 26 apps
- Research read 23 Sept 2026
- How the order is worked out
- 1
Apache Beam
Free plan Open source APILinuxMac+3Apache Beam provides a common programming model for batch and streaming pipelines across several runners. The model is free, though the chosen runner and infrastructure can carry execution costs.
- 2
Apache NiFi
Free plan Open source APILinuxMac+3NiFi combines visual flow management with provenance tracking, flow controls, and a range of documented integrations.
- 3
Arroyo
Free plan Open source APILinuxMac+2Arroyo combines SQL-based streaming, recovery features, and a broad connector list in a self-hostable engine. Plan for a distributed cluster for production use.
- 4
Esper
Free plan Open source APILinuxMac+2Choose Esper if you are building Java or .NET software that needs complex event processing with SQL-derived event queries and an embeddable runtime.
- 5
- 6
Apache Flink
Free plan APILinuxSelf-hostedApache Flink offers stream and batch processing APIs with operational capabilities for self-hosted deployments.
- 7
Apache Spark
Free plan APILinuxMac+2Apache Spark combines distributed analytics, SQL, machine learning and multiple deployment options in a free engine.
- 8
Apache Storm
Free plan APILinuxMac+3Apache Storm provides a free, open-source approach to multi-stage stream processing with a range of integrations and deployment modes.
- 9
Apache Samza
Free plan APILinuxSelf-hostedChoose Apache Samza if you need a free, self-hosted framework for real-time stream processing with state stores, multiple APIs, and built-in integrations.
- 10
Feldera
Free plan APILinuxMac+3Feldera offers a free single-node edition and an enterprise option with multi-node deployments and dedicated support. Check connector status and the deployment requirements for the edition you need.
- 11
Apache Kafka
Free plan APISelf-hostedChoose Apache Kafka if you need a free, open-source stream-processing system that supports stateful processing and event-time windows and can be self-hosted.
- 12
Confluent Cloud
Free plan APILinuxWebConfluent Cloud combines managed Kafka streaming with connectors, stream processing, and governance options.
- 13
Hazelcast Platform
Free plan APILinuxMac+2Choose Hazelcast Platform for real-time applications that need distributed compute, an in-memory data store, and streaming capabilities in one runtime.
- 14
Kafka Streams
Free plan LinuxMacSelf-hosted+1Kafka Streams provides stateful processing tools for applications built around Kafka, with deployment options from one machine to distributed workloads.
- 15
Materialize
Free plan APILinuxSelf-hosted+1Materialize combines incremental SQL processing with managed and self-managed deployment options. Review the Community Edition limits and separate Cloud usage charges before choosing a plan.
- 16
Apache Heron
Free plan LinuxSelf-hostedHeron may suit teams that need its specific stream-processing model, Storm compatibility and self-hosted scheduler choices.
- 17
RisingWave
Free plan APILinuxMac+2RisingWave combines SQL access with incremental streaming views and an exactly-once processing guarantee.
- 18
Timeplus
Free plan APILinuxMac+3Timeplus brings streaming SQL, historical data processing, integrations, dashboards, and alerts into a platform with several deployment options.
- 19
Pathway Live Data Framework
Free plan APISelf-hostedChoose Pathway if you need Python or SQL pipelines that combine live data processing with analytics or AI tooling.
- 20
Quix Streams
Free plan LinuxSelf-hostedChoose Quix Streams if you are building Kafka-based real-time applications in Python and want stateful processing, windowed aggregations or exactly-once guarantees.
- 21
Siddhi
Free plan APILinuxMac+2Siddhi provides a broad set of event-processing operations, integrations, and deployment options for self-hosted use.
- 22
Amazon Managed Service for Apache Flink
Paid APIWebAmazon Managed Service for Apache Flink combines managed operations with broad language and connector support for streaming workloads.
- 23
ksqlDB
Free plan Web - 24
Timely Dataflow
Paid APISelf-hostedTimely Dataflow offers a Rust model for streaming computation that spans local threads and cluster execution. Its documentation caveat is worth noting when getting started or adapting examples.
- 25
Azure Stream Analytics
Paid WebAzure Stream Analytics combines streaming, stateful, and SQL processing with event-time windows.
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#1Places #1, #2, #3, #4, #5 on this list can be bought by the makers of the software on it. See the price
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