Best Stream Processing Software in 2026
Updated
In short: AFL++ is ranked #1 of 24 as of 4 October 2026, ahead of Apache Beam and Apache NiFi. The best-ranked option with a free plan is Apache Beam. The lowest first paid tier on this page is Materialize at $0.13/mo.
Stream processing software works with data as it arrives, so compare how tools handle events and where they can run. Deployment model, source connectors, and SQL processing describe important parts of the setup; event-time windows and stateful processing help distinguish processing capabilities. Supported languages may help narrow options for your team, while free plans and paid starting prices add cost context. AFL++, Apache Beam, and Apache Storm lead the entries, followed by Feldera and Kafka Streams. Check the listed connectors and processing features against the needs of your data pipelines.
24 stream processing software ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
15 of the 24 here have a free tier you can use, 0 have open-source code on record, and 0 have full bars: free, open, on most of your devices and documented.
| # | App | Signal | Free tier | Open code | Devices | From | Score |
|---|---|---|---|---|---|---|---|
| 1 | AFL++Windows · Mac · Linux · Android · Self-hosted | Three bars | — | 4 of 6 | €1666.67/mo | 6.6 | |
| 2 | Apache BeamWeb · Windows · Mac · Linux · Self-hosted · API | Three bars | — | 4 of 6 | Free | 6.6 | |
| 3 | Apache NiFiWeb · Windows · Mac · Linux · Self-hosted · API | Three bars | — | 4 of 6 | Free | 6.6 | |
| 4 | Apache StormWeb · Windows · Mac · Linux · Self-hosted · API | Three bars | — | 4 of 6 | Free | 6.6 | |
| 5 | ArroyoWeb · Mac · Linux · Self-hosted · API | Three bars | — | 3 of 6 | Free | 6.6 | |
| 6 | FelderaWeb · Windows · Mac · Linux · Self-hosted · API | Three bars | — | 4 of 6 | Free | 6.6 | |
| 7 | Kafka StreamsWindows · Mac · Linux · Self-hosted | Three bars | — | 3 of 6 | Free | 6.6 | |
| 8 | TimeplusWeb · Windows · Mac · Linux · Self-hosted · API | Three bars | — | 4 of 6 | $199/mo | 6.6 | |
| 9 | Apache SparkWindows · Mac · Linux · Self-hosted · API | Three bars | — | 3 of 6 | Free | 6.5 | |
| 10 | Confluent CloudWeb · Linux · API | Two bars | — | 2 of 6 | $385/mo | 6.5 | |
| 11 | EsperWindows · Linux · Self-hosted · API | Two bars | — | 2 of 6 | Free | 6.5 | |
| 12 | MaterializeWeb · Linux · Self-hosted · API | Two bars | — | 2 of 6 | $0.13/mo | 6.5 | |
| 13 | Apache FlinkLinux · Self-hosted · API | Two bars | — | 1 of 6 | Free | 6.4 | |
| 14 | Apache SamzaLinux · Self-hosted · API | Two bars | — | 1 of 6 | Free | 6.4 | |
| 15 | Pathway Live Data FrameworkSelf-hosted · API | Two bars | — | 0 of 6 | Free | 6.4 | |
| 16 | Hazelcast PlatformWindows · Mac · Linux · Self-hosted · API | Two bars | — | — | 3 of 6 | — | 5.6 |
| 17 | RisingWaveWeb · Mac · Linux · Self-hosted · API | Two bars | — | — | 3 of 6 | $0.23/mo | 5.6 |
| 18 | SiddhiMac · Linux | No signal | — | — | 2 of 6 | — | 5.3 |
| 19 | Apache KafkaNo platforms listed | One bar | — | — | 0 of 6 | — | 5.2 |
| 20 | Quix StreamsNo platforms listed | No signal | — | — | 0 of 6 | — | 5.1 |
| 21 | Amazon Managed Service for Apache FlinkWeb · API | One bar | — | — | 1 of 6 | — | 5.0 |
| 22 | Timely DataflowNo platforms listed | No signal | — | — | 0 of 6 | — | 5.0 |
| 23 | Apache HeronNo platforms listed | No signal | — | — | 0 of 6 | — | 4.8 |
| 24 | Google Cloud DataflowWeb | No signal | — | — | 1 of 6 | — | 4.7 |
Is your app on this list?
Numbered spots on this list can be sponsored. They are labelled, and the editorial order and scores never change for payment.
Questions about this list
Which stream processing software is ranked first on Freedom251?
AFL++ is ranked #1 of 24 with a score of 6.6. Apache Beam is second and Apache NiFi third.
How many of these have a free plan?
15 of the 24 on this page publish a free plan on their own pricing pages.
Which is the cheapest paid option?
On this page, Materialize has the lowest first paid tier we found: $0.13/mo.
How is this list ranked?
Ranked free-and-open first: a usable free tier and open-source code, then the platforms it runs on and its documentation. Paid placements never change a rank.