Everything runs on your device. That is a deliberate choice rather than a limitation we have not got around to fixing, and it decides most of the answers on this site.
Your playlist is never uploaded. When you open a file or paste an address, the parsing happens in your browser. Playlists, favourites and settings are written to this browser’s local storage on this device. They are not sent to us, because there is no account to attach them to and no server-side store to put them in.
Playback is a direct connection between the source you chose and your browser. No stream passes through our infrastructure: we run no proxy, no relay and no cache for video data.
That design has real costs, and it would be dishonest to list the benefits alone:
- Clearing your browser data deletes your playlists. Export a file for anything you want to keep.
- Your playlists do not follow you to another device.
- A stream whose server refuses cross-origin requests will not play here, because the browser will not permit it. That is a property of the source and not something we can work around. The playback guide covers how to tell that case apart from a stream that is simply dead.
Accounts and a server would remove the first two. We have not added them, because the moment a server holds your playlists there is something to leak, something to be compelled to produce, and something to hand over. There is not.