Here at 9elements we are using Ruby on Rails for most of our web projects. Ruby on Rails is a robust software framework that enables efficient development of web applications. We love to develop with Ruby on Rails because it helps us to develop a web application in a maintainable way:
We use the right tools for the job. Many of our clients are startups or startup-like projects. A startup usually operates with short release cycles. It needs to stay flexible with regards to a particular implementation. Sometimes business models change - and when they do the company relies on a technical environment that allows quick adjustments. Ruby on Rails is pretty strong on such a mindset.
In contrast: if you want to do something with realtime we suggest to checkout Node.js which is more suitable to develop realtime applications. If your application has tough requirements on concurrency, you might choose a functional language like Erlang or Clojure. As we have said in the beginning: we use the right tool for the job.
Ruby on Rails is open source - but it is not the only open source framework that we are using. Our current web development stack looks like this:
...and many more. But 9elements is not only taking - we are also contributing to open source. We created the template engine HAML-Coffee and the frontend framework Chaplin.js to enable other developers to create the most awesome web applications that are out there.