Apache Storm is a free and open source project licensed under the Apache License, Version 2.0

Apache Storm has a large and growing ecosystem of libraries and tools to use in conjunction with Apache Storm including everything from:

  1. Spouts: These spouts integrate with queueing systems such as JMS, Kafka, Redis pub/sub, and more.
  2. 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
  3. Database integrations: There are helper bolts for integrating with various databases, such as MongoDB, RDBMS's, Cassandra, and more.
  4. Other miscellaneous utilities

The Apache Storm documentation has links to notable Apache Storm related projects hosted outside of Apache.