ActiveMQ vs Sparrow: What are the differences?
Developers describe ActiveMQ as "A message broker written in Java together with a full JMS client". Apache ActiveMQ is fast, supports many Cross Language Clients and Protocols, comes with easy to use Enterprise Integration Patterns and many advanced features while fully supporting JMS 1.1 and J2EE 1.4. Apache ActiveMQ is released under the Apache 2.0 License. On the other hand, Sparrow is detailed as "A really fast lightweight queue written in Ruby that speaks memcache". Sparrow keeps messages in memory, but persists them to disk, using Sqlite, when the queue is shutdown.
ActiveMQ and Sparrow can be categorized as "Message Queue" tools.
ActiveMQ is an open source tool with 1.5K GitHub stars and 1.05K GitHub forks. Here's a link to ActiveMQ's open source repository on GitHub.