TinyMCE is a powerful and stable WYSIWYG HTML editor. It comes with more than 40 editing tools and premium features such as improved spell check, file management and upgraded copy-paste.
Amino is a live CSS editor for writing user style sheets. Customize your favorite sites, save and sync your styles using Chrome Sync.
AxMath is an interactive WYSIWYG equation editor. It enables you to type formulas faster than handwriting. It has all kinds of functionalities which make you type equations at lightspeed. Key features include semantic math input, auto calculation, LaTeX conversion, memory board, etc. It currently supports Win7/8/10 and Office 2010-2016.