If we advocate the web, develop for the web, and move more and more of the applications we use every day to the web -- then why are we still developing software using desktop IDEs and desktop code editors? Don't all the advantages of the web apply to IDEs as well? Nothing to install, nothing to configure, seamless software updates, real-time collaboration with other users, offloading computationally expensive tasks (like large compiles) to the cloud. It seems to make perfect sense. Still, nobody seemed to do it. So, we decided to do it ourselves -- building an IDE in the browser. The result: Cloud9 IDE (c9.io).