Jackett

Jackett lets you use a bunch of additional torrent providers with Sonarr, Radarr, SickRage, CouchPotato, and other apps.

It turns your Windows home media server into a Torznab API server which the app can interact with. Jackett queries the torrent providers and supplies information to the app for processing. It supports various public trackers, semi-private trackers, and private trackers.