What are the best academic citation tool

What is the best academic citation tool does anyone help?

Here, we list 2 choices that are open source, or free, or have free plans.

Zotero

Zotero is open source and developed by an independent, nonprofit organization. Zotero can help you collect, organize, cite, and share research. Zotero can automatically senses research on the web. You can sort items into collections and tag them with keywords. Zotero creates references and bibliographies for any text editor, and directly inside Word, LibreOffice, and Google Docs, with support for many citation styles.

Mendeley

You can store all your references in one place and build your personal library to organize, search and read all your references. You can also use citation add-in for Word for referencing, inserting references and bibliographies into your document. You can also easily annotate documents in your library.