React Draft Wysiwyg - Out of the box, feature-rich content editing for React
Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.
Edtr.io - Intuitive WYSIWYG web editor, open source & fully adaptable.
MJML - The open source framework for responsive emails
Froala Editor - Froala Editor is a WYSIWYG HTML editor that enables rich text editing capabilities for the applications.
Stripo - Stripo is an all-in-one email design platform. We enable our clients to build emails of any complexity, including interactive AMP emails, really fast and easy.