* [Regexr](http://regexr.com/) - RegExr is a HTML/JS based tool for creating, testing, and learning about Regular Expressions. ([Source code](https://github.com/gskinner/regexr/)) `MIT``Nodejs`
* [Repo.js](http://darcyclarke.me/dev/repojs/) - A plugin to embed Github repos on your site ([Source code](https://github.com/darcyclarke/Repo.js))
* [RStudio Server](https://www.rstudio.com/products/rstudio/#Server) - web browser based IDE for R. ([Source code](https://github.com/rstudio/rstudio/)) `AGPLv3``Java/C++`