With the rapid proliferation of online citizen science web sites, Azavea, a geospatial software engineering firm, and SciStarter, an online community for citizen science, have collaborated to evaluate a representative set of online citizen science software tools. Supported by the Alfred P. Sloan Foundation, the evaluation effort has analyzed existing online citizen science web sites for their technology, extensibility, visualization, authentication and gamification features in order to better understand their ability to support a diverse and growing catalog of citizen science projects. This blitz session will feature highlights from this evaluation and mark the release of a formal report.