WindowSizer is a subscription-based tool designed for Firefox users engaged in web development. This application allows users to create and manage custom window size presets, enhancing their workflow by enabling quick adjustments to browser dimensions. With features such as a toolbar menu for easy access and customizable hotkeys, users can swiftly switch between predefined settings tailored to their specific needs. Additionally, the ability to edit existing presets and reorder them adds a layer of flexibility to the user experience.

The application also offers quick-fill functionality, allowing users to set preset values based on the current window size, which can save time during testing and development. Backup and restore options ensure that users can maintain their settings without risk, while Firefox Sync support facilitates seamless integration across devices. With both light and dark theme icons, WindowSizer is visually adaptable to user preferences.