Overseerr is a free and open source software application for managing requests for your media library. It integrates with your existing services such as Sonarr, Radarr and Plex!
The qBittorrent project aims to provide an open-source software alternative to µTorrent.
Prowlarr is a indexer manager/proxy built on the popular arr .net/reactjs base stack to integrate with your various PVR apps. Prowlarr supports both Torrent Trackers and Usenet Indexers. It integrates seamlessly with Sonarr, Radarr, Lidarr, and Readarr offering complete management of your indexers with no per app Indexer setup required (we do it all).