#5 Codeacademy

The site says “Codecademy is a team of hackers working hard to build a better way for anyone to teach, and learn, how to code. We're determined to succeed in realizing our mission to turn a world of tech consumers into one of empowered builders.”

Codecademy offers free online coding classes in programming languages like Python, JavaScript, and Ruby, as well as markup languages including HTML and CSS. As of September 2011, the site had over 550,000 users who had completed over six million exercises.

To motivate users to participate, the site offers feedback, badges for completing exercises, as well as a function that keeps track of a user's total score and displays it to others. The site also allows anyone to create and publish a new course using a Course Creator tool. Unlike some of these other online education platforms, Codeacademy focuses solely on teaching coding.

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