The service provides spelling suggestions, including alternatives spellings, for words provided as part of a request. It can draw recommendations either from a collection of dictionaries or from a particular one specified in a request. Dictionaries focused on particular fields and topic domains help to accommodate differences in use of the same word in varying contexts.
API methods support submission of a word as a string in the request URL to return a list of close matches from the service's master dictionary. Methods also support restriction of a request to field-specific dictionaries for biology, earth sciences, mathematics, and library science. Returned data then list only the words that closely match the requested string as used within that particular discipline.