As a developer, it's essential that I have access to a clearly documented API (at least) to read and (possibly) to write/update the financial data.

Specifically, the need to generate reports and analyze data in new ways is essential, and while many systems try to give some sort of "report builder", which are perhaps useful for some needs, are never adequate to foresee every type of necessary issue.

The API should allow for not only custom reports, but the ability to generate a programmatic analysis. For example, this sort of API would be used to compute the ?public support test for USA 501(c)(3) organizations.