Video.js - open source HTML5 & Flash video player

Very simple browser operative system in javascript. Applications are executed in Workers.

Lightweight Javascript WebGL library for handling Context, Meshes, Textures and Shaders. Relies on glMatrix 2.0, very easy to use.

2D Game Engine in WebGL

Collada parser in javascript. It supports skinning, morph targets and bone or node animation. It can parse inside a worker.

Tiny JavaScript logging library, simple and well documented. Lots of options to filter logging data.

A simple script in nodejs to send MIDI notes sequences to a midi output

Javascript Library to create webapps with a desktop look-alike interface. All the widgets are created from Javascript instead of using HTML.

frame-by-frame stepping plugin for use with video.js

Games host server in nodejs, it helps creating persistent online games by providing a dashboard to invite players, launch instances and check stats.

Simple WebSockets server in nodejs that bounces packets with some extra functionality (rooms and http request to store permanent information)

A WebGL 3D Engine library with component-based node hierarchy. Used by WebGLStudio

An inmediate mode GUI that works on top of Canvas2D (it can also work in WebGL)

A lightweight web IDE (mostly a coding editor) based in monaco-editor (with a one-file server made in php). It allows to navigate the server with commands.

Lightweight 3d physics engine for javascript

Ports (almost) all Canvas2D functions to the GPU so it can be mixed with a WebGL canvas.

A cross-platform 3D physics engine

A full open source 3D graphics editor in the browser, with scene editor, coding pad, graph editor, virtual file system, and many features more.

A graph node engine and editor written in Javascript similar to PD or UDK Blueprints, comes with its own editor in HTML5 Canvas2D. The engine can run client side or server side using Node. It allows to export graphs as JSONs to be included in applications independently.