Hanzi Writer is a free and open-source javascript library for Chinese character stroke order animations and stroke order practice quizzes. Works with both simplified and traditional characters.
Hanzi Writer uses character data from the Make Me a Hanzi project, providing over 9000 of the most common simplified and traditional characters.
The Hanzi Writer library is only 35 kb (just 10kb gzipped!), so it won't add bloat to web pages and apps.
Hanzi Writer uses javascript, HTML5 and SVG, so it can be embedded into almost any application, whether an iOS or Android app, or a webpage.