Zooniverse - Largest platform for people-powered research; volunteers help classify data across many disciplines.

Scistarter - Connects volunteers with citizen science projects in need of public participation and data contributions.

FromThePage - Platform for transcribing historical documents with help from volunteers and public archives.

LanguageArc - Supports language documentation through crowdsourced audio, translation, and comprehension tasks.

CitizenScience.gov - U.S. government portal for discovering federally supported crowdsourcing and citizen science projects.