Rich-text editors

TinyMCE is the world’s most popular open source web-based WYSIWYG editor.

Quill is a free, open source WYSIWYG editor built for the modern web. With its modular architecture and expressive API, it is completely customizable to fit any need.

The Summernote Editor is a free & open-source super simple WYSIWYG editor based on Bootstrap & jQuery. It is a JavaScript library that can be useful to build the WYSIWYG editors online. It is maintained under MIT license by a large community. It is easy to use & contains many customizable options.