CODECAST - HTML & CSS editor in your browser with real-time previews
Vectr - Free vector graphics editor. A simple yet powerful web and desktop cross-platform tool for everyone.
StackEdit - Full-featured, open-source Markdown editor based on PageDown, the Markdown library used by Stack Overflow and the other Stack Exchange sites.
Vectornator - A vector-based design software that allows you to create sophisticated graphics, amazing layouts...
CodePen - A front end web development playground.
Amadine - A robust, vector drawing app for Mac