Cleanmock - Create stunning mockups that make your design standout.
CKEditor - Real-time collaborative future-ready rich text editor
The Mockup Club - Get the best design mockups for free
Edtr.io - Intuitive WYSIWYG web editor, open source & fully adaptable.
shotsnapp - Create beautiful device mockup presentation
Summernote - Summernote is a JavaScript library that helps users create WYSIWYG editors online.