Apache Storm is a free and open source project licensed under the Apache License, Version 2.0
Storm has a large and growing ecosystem of libraries and tools to use in conjunction with Storm including 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
The Storm documentation has links to notable Storm-related projects hosted outside of Apache.