Is Storm free and open source?
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Yes. Storm is free to use for open source and commercial projects alike. It was released in 2011 under the permissive Eclipse Public License, and since joining the Apache Software Foundation it has been licensed under the Apache License 2.0. The source code is public, and the project is developed in the open as Apache Storm.
Storm is a free and open source project licensed under the Eclipse Public License. The EPL is a very permissive license, allowing you to use Storm for either open source or proprietary purposes. Storm is hosted on GitHub.
(As of 2012. Storm is now licensed under the Apache License 2.0 and hosted at github.com/apache/storm.)
Storm has a large and growing ecosystem of libraries and tools to use in conjunction with Storm. The storm-contrib project is a central repository for community contributions. However, many community members also choose to host Storm-related projects outside of storm-contrib. Everything in storm-contrib is licensed under the Eclipse Public License. storm-contrib contains everything from:
- Spouts: These spouts integrate with queueing systems such as JMS, Kafka, Redis pub/sub, and more.
- storm-state: storm-state makes it easy to manage large amounts of in-memory state in your computations in a reliable by using a distributed filesystem for persistence
- Database integrations: There are helper bolts for integrating with various databases, such as MongoDB, RDBMS's, Cassandra, and more.
- Other miscellaneous utilities
(As of 2012. storm-contrib is no longer updated. Most integrations now ship with Apache Storm itself.)
The Storm wiki has links to other notable Storm-related projects hosted outside of storm-contrib.