ActivityWatch is a free and open-source automated time tracker that can be used to track how you spend time on your devices. It is cross-platform, extensible, and privacy-first, and can be used to keep track of your productivity, time spent on different projects, bad screen habits, or just to understand how you spend your time. It offers features such as tracking active applications and window titles, categorizing usage, browser extensions, editor plugins, and more. Users have generally given positive reviews of ActivityWatch, praising its value, features, and privacy-first approach.