Zooniverse is a citizen science web portal owned and operated by the Citizen Science Alliance. It is home to some of the internet's largest, most popular and most successful citizen science projects. The organization grew from the original Galaxy Zoo project and now hosts dozens of projects which allow volunteers to participate in crowdsourced scientific research. It has headquarters at Oxford University and the Adler Planetarium.
As of 14 February 2014, the Zooniverse community consisted of more than 1 million registered volunteers. By March 2019, that number had reportedly risen to 1.6 million. The volunteers are often collectively referred to as "Zooites". The data collected from the various projects has led to the publication of more than 100 scientific papers.