Abacus is a free productivity tool that is available as a browser extension and native app. By using the built-in tracking feature of your browser, Abacus can keep a track of all your websites. Whenever you start the browser, it will track the current site you are visiting. Abacus also has an integrated "Are you sure" dialog which allows you to keep track of which website you're going to and to easily navigate to another one. When you close the browser, all the websites that were tracked are shown on your desktop, making it easy to navigate through them. It also has a function to stop tracking a site and remove it from the list.