Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
CKEditor - Real-time collaborative future-ready rich text editor
Joplin - Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, tagged and modified either from the applications directly or from your own text editor.
Summernote - Summernote is a JavaScript library that helps users create WYSIWYG editors online.
Google Keep - Capture notes, share them with others, and access them from your computer, phone or tablet. Free with a Google account.
Froala Editor - Froala Editor is a WYSIWYG HTML editor that enables rich text editing capabilities for the applications.