Open in PDF Viewer is a lightweight Firefox addon designed to streamline the process of opening PDF files directly in preferred PDF viewers. Compatible with various operating systems including Windows, Linux, and Mac, it requires users to connect the addon to their native PDF applications post-installation. This is facilitated by a patch available on GitHub, ensuring that the addon can communicate seamlessly with your installed PDF viewer. The default viewer is Adobe Acrobat Reader, but users have the flexibility to customize their viewer settings, including input arguments for specific viewing preferences.

To utilize the addon, users simply right-click on any PDF link and select the 'Open and Download with PDF Viewer' option from the context menu. The PDF file is then downloaded to the default downloads folder and opened in the designated viewer. It is essential for users to verify and correct the path to their PDF viewer in the options page to ensure proper functionality. This addon enhances productivity for individuals frequently working with PDF documents by simplifying access and customization.