Processing.js is an open programming language for people who want to program images, animation, and interactions for the web without using Flash or Java applets. Processing.js uses Javascript to draw shapes and manipulate images on the HTML5 Canvas element. The code is light-weight, simple to learn and makes an ideal tool for visualizing data, creating user-interfaces and developing web-based games.

Processing.js runs in FireFox, Safari, Opera, Chrome and will also work with Internet Explorer, using Explorer Canvas.

The Processing language was created by Ben Fry and Casey Reas. It evolved from ideas explored in the Aesthetics and Computation Group at the MIT Media Lab and was originally intended to be used in a Java run-time environment.

In the Summer of 2008, John Resig ported the 2D context of Processing to Javascript for use in web pages. Much like the native language, Processing.js is a community-driven project, and continues to grow as browser technology advances.