deepstream.io vs Radar: What are the differences?

deepstream.io: A scalable server for realtime webapps. Scalable Server for Realtime Web Apps with JSON structures that can be read, manipulated and listened to, messages that can be sent to one or more subscribers, and request response workflows, between two clients or servers; Radar: High level API and backend for writing web apps that use push messaging. Radar is built on top of engine.io, the next-generation backend for socket.io. It uses Redis for backend storage, though the assumption is that this is only for storing currently active data.

deepstream.io and Radar belong to "Realtime Backend / API" category of the tech stack.

Some of the features offered by deepstream.io are:

• Stores and syncs data in realtime
• Built in node.js
• Works for browsers, backend & mobile

On the other hand, Radar provides the following key features:

• More than just pub/sub: a resource-based API for presence, messaging and push notifications via a Javascript client library
• Written in Javascript/Node.js, and uses engine.io (the new, low-level complement to socket.io)
• Backend to multiple front-facing servers

deepstream.io and Radar are both open source tools. It seems that deepstream.io with 6.14K GitHub stars and 315 forks on GitHub has more adoption than Radar with 209 GitHub stars and 35 GitHub forks.