StudyStack is a web site that lets visitors use their computer to display a stack of "virtual cards" which contain information about a certain subject. Subjects include, Geography, History, Math, Languages, Science, and Medicine. StudyStack provides a REST API to access the flashcards entered by the users of the site. The API can return an array of a user's stacks, contents of a stack, categories and stacks within a category. Responses are formatted in JSON. Any data returned from the studystack API must not be made visible to search engine robots.