No. You don't have to download or install anything to be able to access or run New Sloth.
New Sloth is a Web-based application, which means that all you need to use it is a modern Web browser (like Google Chrome, Firefox or Microsoft Edge) and an Internet connection. It runs from our fast, reliable and secure servers.
You can access the web app on any device, including a desktop PC, laptop/notebook, tablet, smartphone or even a TV.