Although an Integrated Development Environment (IDE) is not always essential for data science, building data products often requires a complete development environment and not just statistical analysis. In my quest to be able to perform all my web development and data science work on a chromebook, it is essential to have a development environment in the browser. Luckily for me and for all of you, there are a number of companies working on just that. Full disclosure: Some of the links below contain my referral codes.

Name Languages Supported Ruby, Node.js, Python, PHP or Go
CodeBox PHP, Java, Ruby, Node.js, Python, Go, C/C++, and many more
Koding ?
Codio PHP, Node.js, Ruby, many others
Cloud9 IDE Node.js, PHP, and many more
Runnable Java, PHP, Python, and more
Codeanywhere ?

Disclaimer, I have not had a chance to try out each of the options, but I thought I should share anyhow.