Teachable - Create and sell beautiful online courses with the platform used by the best online entrepreneurs to sell $100m+ to over 4 million students worldwide.

RegExr - RegExr.com is an online tool to learn, build, and test Regular Expressions.

Clever - syncing between education applications for K-12 schools

Expresso - The award-winning Expresso editor is equally suitable as a teaching tool for the beginning user of regular expressions or as a full-featured development environment for the experienced programmer with an extensive knowledge of regular expressions.

Claroline - Claroline is a collaborative eLearning and eWorking platform.

rubular - A ruby based regular expression editor