Zotero

Zotero is a free, open-source reference manager from the non-profit Corporation for Digital Scholarship, and it remains the default recommendation for researchers who want their bibliography under their own control. A browser connector captures references from journal pages in one click, the built-in PDF reader supports annotation, the Word and LibreOffice plugins handle citations across thousands of styles, and group libraries make collaborative projects straightforward. Two things worth knowing. Because it is open source and non-profit, there is no upsell, no premium tier gating core features, and no risk of a commercial owner changing terms later, which is the main reason researchers pick it over Mendeley. And the free storage allowance is modest, with paid tiers available, though many users sync files through their own cloud storage instead and keep Zotero entirely free.