Colossus vs ExpressJS: What are the differences?

Colossus: I/O and Microservice library for Scala. Colossus is a lightweight framework for building high-performance applications in Scala that require non-blocking network I/O. In particular Colossus is focused on low-latency stateless microservices where often the service is little more than an abstraction over a database and/or cache. For this use case, Colossus aims to maximize performance while keeping the interface clean and concise; ExpressJS: Sinatra inspired web development framework for node.js -- insanely fast, flexible, and simple. Express is a minimal and flexible node.js web application framework, providing a robust set of features for building single and multi-page, and hybrid web applications.

Colossus and ExpressJS can be categorized as "Microframeworks (Backend)" tools.

Some of the features offered by Colossus are:

• Clean Event-based Programming
• Seamless Integration with Akka
• Real-time Metrics

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

• Robust routing
• HTTP helpers (redirection, caching, etc)
• View system supporting 14+ template engines

Colossus and ExpressJS are both open source tools. It seems that ExpressJS with 44.6K GitHub stars and 7.48K forks on GitHub has more adoption than Colossus with 1.14K GitHub stars and 100 GitHub forks.