Bear in Mind is a free to-do list you can use straight in your browser, with nothing to install and no account to make. Write down the tasks and reminders you do not want to forget, add a longer note to any of them, and tick them off as you go. Your list is saved in your own browser and is still there the next time you open the page. There is also a Windows app and a browser extension, and a list can be exported from one and imported into another.