MOBI Reader is a robust browser extension designed specifically for Firefox that allows users to open and view MOBI files seamlessly. Users can access documents by right-clicking on any MOBI link and selecting the 'View MOBI' option from the context menu, or by using the popup interface to input links directly. For offline reading, files can be easily dragged into the designated area of the popup, making it convenient to access documents without an internet connection.

The extension boasts a dark mode, enhancing the reading experience during nighttime use, while the adjustable window size allows documents to adapt to user preferences. Utilizing an open-source JavaScript library called mobi.js, MOBI Reader effectively renders MOBI files, which are primarily used for Kindle devices. This extension is a valuable tool for anyone looking to read e-books or documents in the MOBI format.