Which programming framework was used to build Twitter’s early web application?

Twitter’s early web application was built using the Ruby on Rails programming framework.

Ruby on Rails, often shortened to Rails, is a web application framework written in Ruby. Twitter’s early development used Rails because it allowed a small team to build and iterate on a rapidly changing service quickly. The platform began as a side project associated with the podcast company Odeo and initially had relatively modest technical demands.

As Twitter’s user base expanded, the service experienced severe scaling challenges, including slow performance and frequent outages. Engineers gradually introduced additional technologies and services, and Twitter moved important parts of its infrastructure away from a purely Rails-based architecture. That later evolution does not change the framework’s role in the site’s early history.

Ruby on Rails is therefore best understood as the framework behind Twitter’s original web application, not the only technology used by the mature company. This distinction avoids the common misconception that Twitter continued running entirely on its first stack.