Citizen Audit is a good alternative to guide star. Edit :
The search process is less click hungry.
Getting several fiscal years at a time is possible on a unique page.
- More fiscal years available for IRS 990. ( generally go until 2005/2006, where guidestar give, in most case, the last 3 years.
- API and bulk access are a possibility ( if you subscribe to a plan )
- On the result page, you have a OCR version of the document, for handy ctrl+f textual research.
- Some PDF are polluted by banners on top. ( Not-blocking, but annoying. Easily crop-able though )