Pell is the simplest and smallest WYSIWYG text editor for web, with no dependencies.
Trix is a WYSIWYG editor for writing messages, comments, articles, and lists—the simple documents most web apps are made of. It features a sophisticated document model, support for embedded attachments, and outputs terse and consistent HTML.
Jodit Editor is a beautiful and functional WYSIWYG HTML text editor with file browser out-of-box.
It's free for non-commercial use.
Kajero notebook is just a Markdown document with a script attached. Kajero is designed to make it really easy for anyone to create good-looking, responsive, interactive documents.
Easy Editor is a lightweight and highly configurable rich text html editor. You can use fontawesome icons on buttons area and also can upload and insert image on editor.
Simditor is a browser-based WYSIWYG text editor. It's based on jQuery.
Markdownify is the simplest markdown editor with built in cloudinary image upload.
Bootstrap Markdown is a plugin for markdown editing. It exposes useful API that allow you to fully hook-in into the plugin.
wysiwyg.js is a lightweight content editable jQuery editor which works with legacy browsers.