StreamSaver.js takes a different approach. Instead of saving data in client-side storage or in memory you could now actually create a writable stream directly to the file system (I’m not talking about [Chrome’s] sandboxed file system or any other web storage). This is accomplish by emulating how a server would instruct the browser to save a file using some response header + service worker
StreamSaver.js is the solution to saving streams on the client-side. It is perfect for webapps that need to save really large amounts of data created on the client-side, where the RAM is really limited, like on mobile devices.
FileSaver.js is the solution to saving files on the client-side, and is perfect for web apps that generate files on the client.