Marks: Text Highlighter is a Firefox extension designed to assist users in efficiently reading, researching, and organizing web content. It allows users to highlight key text directly from an intuitive in-page control interface, applying color highlights with a single click. The extension supports a multi-color system, starting with five default colors and offering the option to add custom colors to suit individual workflows. Users can utilize right-click context menus or keyboard shortcuts for quick actions, making it adaptable to various working styles.

The highlights are structured by page, ensuring that users can easily return to important information on previously visited URLs. The extension features minimap navigation for quick scanning of highlights, particularly beneficial on lengthy pages. With local-first storage and optional cross-device sync, Marks: Text Highlighter guarantees privacy without requiring a dedicated backend server or user accounts, making it an excellent tool for researchers, students, and knowledge workers seeking a streamlined reading experience.