Where can I find a dataset for Chinese characters to back an app I want to write? I've been spending a lot of time learning chinese, and have some ideas for apps that would make this complicated process easier. 

I'm looking for datasets (ideally free) that I can use to back an app I want to write. 

The dataset should have definitions, character ranks, frequency data, radical composition data etc.

An example of an existing app is http://www.hanzicraft.com/character/%E5%AE%89

Where does one obtain such data? 

Any ideas?

Thanks
Here are some free databases that may be useful to you:


CC-CEDICT: high quality user-created  dictionary released under a Creative Commons Attribution-Share Alike 3.0 License 
SUBTLEX-CH: Chinese word and character frequencies based on film and television show subtitles
Wikimedia Commons Chinese character decomposition database