@kaia
rutracker.org — it's not as good as some specialised music torrent sites might be, but still good — mostly because it's Russian and I think they just ignore takedown notes.
And it's open — the built-in search might not work without an account, but you can always search for "site:rutracker.org whatever-you-want" on DuckDuckGo. Also, it doesn't always allow you to download .torrent files without logging it, but Magnet links always remain public and most Bittorrent software supports them.