CKEditor : CKEditor is an open source WYSIWYG text editor designed to bring common word processor features directly to web pages, simplifying their content creat...
TinaCMS : Tina is an open-source site editing toolkit for React-based sites like Next.js & Gatsby to build content management directly into your website.
Xinha : Xinha is a powerful WYSIWYG HTML editor component that works in all current browsers. Its configurabilty and extensibility make it easy to build just ...
Strut : An HTML5 Presentation Editor. A GUI / Authoring Tool for ImpressJS and Bespoke.js
Source at https://github.com/tantaman/Strut
Bottery : Bottery is a syntax, editor, and simulator for prototyping generative contextual conversations modeled as finite state machines.
WYSIWYG Content Editor, Inline Rich Text Application