Citation generators are programs that can help you craft citations quickly and easily. They are not as robust as full citation managers like Zotero and RefWorks, but can help make quick work of shorter bibliography needs. Choose a citation style and enter the bibliographic details of the works consulted (author, title, publication date, etc.) to automatically create citations.
It is important to note that you must enter data accurately and carefully check the automatically generated citations for errors. As noted in the Purdue OWL's guide to Using Citation Generators Responsibly (linked below), "relying entirely on citation generators rather than on one’s judgment as a writer can lead to errors."