When comparing Codio vs Codepen, the Slant community recommends Codio for most people. In the question“What are the best cloud IDEs?” Codio is ranked 9th while Codepen is ranked 22nd.
Ranked in these QuestionsQuestion Ranking
Pro Designed to teach programming
Pro Fully functional terminal
Codio gives you full access to a terminal, with all the ubuntu commands. You can use the terminal within the page, or you can access by SSH from your computer.
Emmet support for a whole range of features that really boost productivity when working with HTML and CSS. These features include expanding abbreviations into full HTML or CSS as well as some very powerful keyboard shortcuts.
Pro BitBucket integration
It's possible to launch Codio from within BitBucket's repo by adding Codio integration as an add-on.
Pro Server-side environment
Pro Node.js included by default.
Includes Monokai style theme by Luigi Maselli.
Pro Easily export your pen
CodePen makes it really easy to export code as a zip or Github Gist.
Pro Real time output
Pro Lots of support for frameworks and preprocessors
CodePen has an impressive amount of support for preprocessors (such as Jade, Haml, Slim, Sass, Less, Stylus, Coffeescript and PostCSS). There is also plenty of frameworks and libraries to pick from (Foundation, Bootstrap, Angular, D3, Backbone, Ember etc.).
Pro Great display/profile page
The codepen profile page allows you to display all of your public pens, and control which order you want them to be viewed in. This is great for showing off your work to possible employers, other devs etc..
Pro Easily fork pens
To fork a pen only requires clicking one button, and you'll be able to modify the pen on your own account.
Pro Great community pens
You can search through other pens, either by keyword or popular, picked or recent.