What are some alternatives?
When comparing CouchPotato and Radarr, you can also consider the following products
Sonarr - Sonarr (formerly NzbDrone) is a PVR for Usenet and BitTorrent users.
Ombi - Ombi is a front end user facing request system.
Sick Beard - Sick Beard is a PVR for newsgroup users (with limited torrent support).
FlexGet - FlexGet is a multipurpose automation tool for all of your media
Jackett - API Support for your favorite torrent trackers.
Lidarr - Lidarr is a music collection manager for downloading and organizing music libraries.