TinyMCE

Froala Editor is a powerful and highly customizable WYSIWYG HTML Editor written in JavaScript, designed to provide rich text editing capabilities for web applications. This versatile editor offers a clean, intuitive interface combined with a wide array of features, including inline editing, image manipulation, and video embedding. Froala stands out for its performance optimization, ensuring smooth editing experiences even in complex applications. The editor is highly extensible, offering numerous plugins for additional functionality like spell checking, math equations, and code syntax highlighting. With its focus on mobile responsiveness and touch support, Froala Editor provides a consistent editing experience across devices. The editor also offers robust API and events system, allowing for deep integration and customization within web applications. While it's a commercial product, Froala Editor's combination of features, performance, and flexibility makes it a popular choice for projects requiring advanced in-browser editing capabilities.

Etherpad is an open-source, web-based collaborative real-time editor, allowing authors to simultaneously edit a text document, and see all of the participants' edits in real-time, with the ability to display each author's text in their own colour.

Quill is a free, open-source WYSIWYG editor that brings powerful text editing capabilities to web applications. Designed with both simplicity and extensibility in mind, Quill offers a clean, intuitive interface while providing a robust API for customization. The editor supports a wide range of formatting options and features, including real-time collaboration, custom content and formatting, and cross-platform compatibility. Quill stands out for its modular architecture, allowing developers to easily add or remove features to create a tailored editing experience. The editor also focuses on performance, ensuring smooth operation even with large documents. With its support for themes and custom formats, Quill can be styled to match any application's design. Whether used for simple text inputs or complex document editing, Quill's combination of ease of use and powerful features makes it a popular choice for developers looking to integrate rich text editing into their web applications.

CKEditor is a feature-rich, open-source WYSIWYG (What You See Is What You Get) rich text editor that enables the creation of sophisticated content directly within web pages or online applications. Developed by CKSource, this versatile editor offers a wide range of text formatting options, media embedding capabilities, and advanced features like table creation and form integration. CKEditor stands out for its modular architecture, allowing developers to customize the editor's functionality and appearance to suit specific needs. The editor supports real-time collaborative editing, making it ideal for team-based content creation. With its focus on accessibility and cross-browser compatibility, CKEditor ensures a consistent editing experience across different platforms. Available under both open-source and commercial licenses, CKEditor caters to a wide range of projects, from personal blogs to enterprise-level content management systems.

WysiBB very simple and functional open-source WYSIWYG BBCode editor based on jQuery.