Sinatra vs. Sails.js vs. Colossus

Sinatra is a DSL for quickly creating web applications in Ruby with minimal effort.

Sails is designed to mimic the MVC pattern of frameworks like Ruby on Rails, but with support for the requirements of modern apps: data-driven APIs with scalable, service-oriented architecture.

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.