It searches in a lot of indexers (torrent sites) simulatenously. You put the indexers you want to search, connect it to qBittorrent (via a plugin), Radarr, or Sonarr and it searches.
Here in Greece, we have three providers, but I don't want to change, since we pay very little money to the one I am in right now in return of slower speeds (5 Mbps download, 0.5 Upload).
I found an HP EliteDesk 800 G1 SFF at 100€ here. It has an Intel core i5 4th Gen and 8GB of RAM. Not exactly mini but cheap. Do you think it's worth it?
EDIT: nvm I found this used Intel nuc here with the same specs.