Revise.js

Introducing Revise.js, a foundational library for building contenteditable-based web text editors, with a web component that reads the DOM as a string, an algebraic edit data structure, and a declarative component model.

Listed under Productivity, Revise.js is reachable at revise.js.org (freemium (free tier + paid plans)). Keep this overview for a quick scan, then verify features and pricing on the vendor site before committing.