OpenSpending aims to be a simple-to-use platform for developers. The site offers a variety of APIs that can be used to create new visualizations, reports and other applications:
We want to help people answer complicated questions about government finance. If you have used OpenSpending in some interesting way, please let us know and we’ll add your project to this section!
Of course, OpenSpending is an open source project and we aim to include contributions into production as quickly as possible.
We work as a distributed team and most discussions take place either on the openspending-dev mailing list or on IRC (#openspending on FreeNode).
If you feel like hacking core, check out the GitHub issues to see what is going on and where help is needed.