ProseMirror

ProseMirror is a JavaScript library that helps developers create structured rich-text editors for websites. It's not a ready-to-use editor itself, but rather a set of building blocks. You use it to construct an editor that fits your specific needs, whether that's a simple comment box or a complex document editor with custom formatting rules. The documents it produces are clean and semantically meaningful, striking a balance between the rigid structure of Markdown and the free-form nature of a classic WYSIWYG editor.

What sets ProseMirror apart is its architecture. It has first-class support for real-time collaborative editing, allowing multiple people to work on a document simultaneously. Its system is modular and pluggable, so you can load only the components you need and easily add new features through plugins. The core library is intentionally small and unopinionated, providing a flexible foundation. It uses a largely functional and immutable design, which makes it a good fit for modern web applications.

This toolkit is primarily for web developers and engineering teams who need to embed a text editor into their web application. It's used by companies like The New York Times and The Guardian to build their publishing tools. Real-world use cases include building collaborative document editors, content management systems (CMS), note-taking applications, and anywhere else a custom, structured editing experience is required.