EaselJS
EaselJS provides straight forward solutions for working with rich graphics and interactivity with HTML5 Canvas. It provides an API that is familiar to Flash developers, but embraces Javascript sensibilities. It consists of a full, hierarchical display list, a core interaction model, and helper classes to make working with Canvas much easier.
LycheeJS
LycheeJS is an environment-independent JavaScript game engine, which means it will run in any theoretical JavaScript supporting environment. The publishing process is optimized for development inside the Web Browser using the HTML5 platform adapters.
Crafty
Crafty, previously known as CraftyJS, is a small, simple, and lightweight game engine that can greatly help you build prototypal or fully-featured 2D HTML5 games. Crafty is also open-source and completely free. Its code is hosted openly on GitHub.com and is distributed under the MIT or GPL license.
MelonJS
MelonJS is the result of our enthusiasm and past experiments with Javascript, and came from the feeling that no simple, free and standalone library was available to develop games. And although still a work in progress, melonJS already allows to easily create some nice games.
Turbulenz Engine
The engine libraries are implemented in optimised JavaScript supporting rapid iteration of game code and data. The engine executes directly in the browser and includes many features.
Three.js
It does a really great job of abstracting away the headaches of getting going with 3D in the browser. With it you can create cameras, objects, lights, materials and more, and you have a choice of renderer, which means you can decide if you want your scene to be drawn using HTML 5’s canvas, WebGL or SVG. And since it’s open source you could even get involved with the project.
Quintus
Quintus is an easy-to-learn, fun-to-use JavaScript HTML5 game engine for mobile, desktop and beyond! Create an HTML file, pull in the Quintus library and setup the engine. Quintus has a modular engine that lets you pull in just the modules you need and can run in multiple instances on a page.
Playcanvas
Create games that run plugin-free in any modern browser. Hardware-accelerated using WebGL. Running right in your browser, nothing to download and install. Get started in seconds. Real-time collaboration. Work with your team-mates see their changes as they happen. Join the PlayCanvas community and get help making your game. Publish your game to PlayCanvas, share it with the world.
Frozen
Frozen is an open-source HTML5 game engine delivering ease-of-use, rapid development through tooling and modularity. Our goal is to apply techniques used in building modern webapps to game development, such as AMD modules, dependency management, build process, and project scaffolding.
Phaser
Phaser uses both a Canvas and WebGL renderer internally and can automatically swap between them based on browser support. This allows for lightning fast rendering across Desktop and Mobile. Phaser uses and contributes towards the excellent Pixi.js library for rendering.