Tina is an open-source site editing toolkit for React-based sites like Next.js & Gatsby to build content management directly into your website.

Web-based P2P collaborative editor for live coding music and graphics

Bitsy is a little editor for little games or worlds. The goal is to make it easy to make games where you can walk around and talk to people and be somewhere.

A React-powered node editor and runtime engine. Build apps that are resilient to changing requirements by modeling your business logic as a JSON graph. Flume provides a sleek UI for creating and editing these graphs.

CryptPad is the Zero Knowledge realtime collaborative editor.

Encryption carried out in your web browser protects the data from the server, the cloud and the NSA. It relies on the ChainPad realtime engine.

Web-based text editing tool that allows to edit documents collaboratively in real-time. It implements a CRDT-based consistency maintenance algorithm for strings for peer-to-peer large scale collaboration. This algorithm called LogootSplit can be seen as an extension for variable-sized elements (e.g. strings) of one of the basic CRDT algorithms for unit elements (e.g. characters). Compared to existing web-based collaborative text editing tool MUTE does not require a powerful central server since the server is not performing any computation. Communication between editor instances is done in a peer-to-peer manner thanks to the Netflux library that is based on WebRTC technology. Our editor offers support for working offline while still being able to reconnect at a later time.

Firepad is an open-source, collaborative code and text editor. It is designed to be embedded inside larger web applications.

Conclave is a peer-to-peer, real-time, collaborative text editor built from scratch in JavaScript. Intrigued by collaborative text editors such as Google Docs, we set out to build our own. This case study walks you through our journey from the initial idea to our research of current academic literature and finally to our design and implementation of the final product.

Teletype for Atom lets developers share their workspace with team members and collaborate on code in real time.

Bottery is a syntax, editor, and simulator for prototyping generative contextual conversations modeled as finite state machines.

a modern and intuitive terminal-based text editor

Your friendly neighborhood script for mangling images or video using audio editing tools.

Slate is a completely customizable framework for building rich text editors.

Slate lets you build rich, intuitive editors like those in Medium, Dropbox Paper or Canvas—which are becoming table stakes for applications on the web—without your codebase getting mired in complexity.

Floobits brings real-time collaborative editing to text editors, IDEs. Collaborative text editors and screen sharing solutions usually suffer from the following problems:

Users are confined to looking at the same thing.
Only one user can edit at a time.
One person is usually stuck in an unfamiliar editor.
Only 2 people can work at a time.

We started building Floobits for ourselves to address these concerns. Floobits allows multiple users to simultaneously edit any file using the text editors they already know.

Interactive code to flowchart converter. Turn your workflows, algorithms and manuals into easy to understand diagrams via simple code.

The Monaco Editor is the code editor that powers VS Code.
Rich IntelliSense and Validation for TypeScript, JavaScript, CSS, LESS.
Basic Syntax Colorization for HTML, XML, PHP, C#, C++, Razor, Markdown, Diff, Java, VB, CoffeeScript, Handlebars, Batch, Jade, F#, Lua, Powershell, Python, SASS, R, Objective-C.

An HTML5 Presentation Editor. A GUI / Authoring Tool for ImpressJS and Bespoke.js
Source at https://github.com/tantaman/Strut

The simplest app for Bootstrap prototyping. Create quality HTML prototypes quickly, using popular open source tools like Bootstrap, LESS, Fontawesome and more. Work visually and with sources simultaneously, with no need to export. Easily integrates into developers' toolsets (Git, text editors, etc.) Works with plain HTML and LESS files. Generate only standard Bootstrap 3.3 HTML and LESS markup.

A better way to conduct remote interviews
WebRTC based video chat + code editor = Awesome interviews

an open source rich text editor based on HTML5 technology and the progressive-enhancement approach.