[sam_goody]

There are LOTS of competitors, but of course, not all are apples to apples.

Here is a partial list of some of the more active wysiwyg editors:

   Quill: https://quilljs.com
   Slate: https://www.slatejs.org  
   Trumbowyg: https://alex-d.github.io/Trumbowyg
   ContentTools: http://getcontenttools.com
   SummerNote: https://summernote.org
   Squire: https://github.com/neilj/Squire
   Editor.js: https://codex.so/editor
   ProseMirror: https://prosemirror.net/

I have personally been happy with Quill (the have their own system for storing text which is interesting.

Many of these have active branches, especially in Vue or React etc.

[fourstar]

Best I could find would be: https://github.com/chanzuckerberg/czi-prosemirror but they kinda stopped working on it.

[bhl]

An example of a library using React and ProseMirror is from Outline, which is switching from Slatejs: https://github.com/outline/rich-markdown-editor/pull/150.