Library Check for Zotero – Prevent Duplicates — Yukihiro Marui

Library Check for Zotero is a Firefox extension that automatically checks whether the academic paper you are currently viewing is already saved in your Zotero library.

Simply open a paper page, and the extension will compare it with your local Zotero library. If the paper has already been saved, a direct link to the matching Zotero item is displayed. There is no need to manually open Zotero and search for it.

By checking before saving, you can prevent duplicate entries in your library. When a match is found, you can quickly open the saved item to review your notes, confirm details, or continue citation work without interruption.

Key Features

• Read-only design (does not add, edit, or delete items in Zotero)
• Works entirely in your local environment (no external server communication)
• One-click access to matching Zotero items
• Optional on-page overlay display
• Supports 7 languages
• Light and dark theme support

Supported Pages

The extension works on academic paper pages that contain standard scholarly metadata such as a DOI. This includes many publisher platforms, as well as research sites like arXiv and PubMed.

Privacy

This extension communicates only with your local Zotero application on your computer. It does not use cloud services, collect data, or perform any tracking.

Requirements

• Zotero desktop application running
• "Allow other applications on this computer to communicate with Zotero" enabled in Zotero settings (required even if you use the official Zotero Connector)

Notes

• The extension cannot perform checks if Zotero is not running.
• This project is not affiliated with the official Zotero project.