Zotero allows you to collect, save, and manage bibliographic information on books, articles, websites, and more. Once you've got Zotero working, you can use it to create in-text citations and bibliographies in over 7,000 styles with the click of a button. Zotero integrates with Word, Google Docs, or LibreOffice, or can just export a bibliography to pages or any other word processing program.
Zotero is available for Mac, Windows, or Linux. If you're on a Chomebook, iPad, or other mobile device, you can use zBib instead. It's browser-based and should work anywhere.
In addition to Zotero itself, you will need the Zotero connector for whichever browser you use. Connectors are available for Chrome, Safari, Firefox, and Opera.