Sparrow vs EMQ: What are the differences?
Developers describe Sparrow 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. On the other hand, EMQ is detailed as "The Scalable MQTT Broker for IoT and Mobile Applications". It is fully open source and licensed under the Apache Version 2.0. It implements both MQTT V3.1 and V3.1.1 protocol specifications, and supports MQTT-SN, CoAP, WebSocket, STOMP and SockJS at the same time.
Sparrow and EMQ belong to "Message Queue" category of the tech stack.
EMQ is an open source tool with 181 GitHub stars and 96 GitHub forks. Here's a link to EMQ's open source repository on GitHub.