Open in Sumatra PDF and DJVU Reader is a Firefox extension designed to enhance your experience with PDF and DJVU files by integrating seamlessly with the open-source Sumatra PDF application. This extension allows users to easily send links of PDF or DJVU documents directly to Sumatra PDF using two methods: through the right-click context menu on PDF links or by utilizing the browser action button after opening the file in a tab. The process is straightforward and user-friendly, ensuring quick access to documents without complicated procedures.

To function properly, this extension requires a native helper module, which is written in JavaScript and operates with the official NodeJS executable. Upon first use, users will receive instructions on how to install this necessary component. Notably, the extension does not perform any server-side operations apart from downloading the files to the default download directory before sending them to Sumatra PDF, making it a reliable tool for PDF handling without the need for extensive setup.