GitHub Writer is an Open Source browser extension that brings WYSIWYG editing to issues, comments, pull requests, wikis and discussions in GitHub. It accepts Markdown input and offers productive writing, starting with tables.

CKEditor 5 is an ultra-modern JavaScript rich text editor with MVC architecture, custom data model and virtual DOM.

Native integrations with Angular, React and Vue.js, compatible with Electron, iOS and Android.

HangHub is a team productivity tool that allows you to see the users who are working on the same GitHub issue or pull request as you in real time.