The movie half of the *arr stack: Radarr is a .NET collection manager that automates acquiring films for Usenet and BitTorrent users the way Sonarr does for TV. Add a movie once and Radarr handles the rest: it monitors indexers and RSS feeds, grabs a matching release the moment one appears, sends it to SABnzbd, NZBGet, qBittorrent, Deluge, Transmission, rTorrent, or another connected download client, then imports, sorts, and renames the file into your library structure. Quality profiles are the control surface - define allowed resolutions and a cutoff, and Radarr keeps upgrading files automatically, replacing a DVD rip when a Blu-ray release lands. Custom formats go further, scoring releases by codec, HDR metadata, release group, streaming source, or arbitrary regex so the copy you want always wins the pick. Failed downloads retry with another release automatically; a manual search shows every candidate and explains why one was skipped. Release parsing recognizes director's cuts, special editions, AKA titles, and hardcoded subs. Plex and Kodi integration handles notifications, library refreshes, and metadata like posters, trailers, and subtitles, and a calendar view tracks upcoming releases. It pairs naturally with Jellyseerr for request management and shares its API conventions with the whole *arr ecosystem.

Configure each indexer once, not five times: Prowlarr is the indexer hub of the *arr stack, removing the most tedious duplication in a media automation setup. Instead of configuring the same torrent trackers and Usenet indexers separately in Sonarr, Radarr, Lidarr, Readarr, and Mylar3, you add each one once in Prowlarr and it syncs them to every connected app automatically, complete with category mappings; with Full Sync enabled, adding or removing an indexer propagates everywhere, and a tracker URL change is a one-place fix. Coverage is the deepest available: 500+ torrent trackers with definitions added constantly, 24 native Usenet indexers, generic Newznab and Torznab support for anything else, and custom Cardigann YML definitions with JSON and XML parsing for obscure sources. Built on the same .NET/React base as its siblings, it also earns a place as a search tool in its own right: unified manual search queries every indexer simultaneously at a category level, and you can push multiple releases straight to your download clients without touching Sonarr or Radarr. Health checks and status notifications flag failing indexers, per-indexer statistics track success rates and response times so you can cull unreliable sources, and per-indexer proxy support (SOCKS4/5, HTTP, FlareSolverr) handles trackers behind Cloudflare.

Subtitles are the one chore Sonarr and Radarr leave behind - Bazarr finishes the *arr media stack by automating them. It connects to both via their APIs and mirrors their libraries - it doesn't scan disk itself, it manages exactly what your *arr apps index. For every monitored episode and movie it checks existing internal and external subtitles against your language profiles, then hunts missing ones across dozens of providers - OpenSubtitles.com, Podnapisi, Addic7ed, Subscene, and many regional sources - covering 184 subtitle languages including forced/foreign-dialogue tracks. Matching is smarter than filename guessing: releases are compared by release group and source, some providers support exact file-hash matching, and every downloaded subtitle gets a percentage score. Set a minimum score per Sonarr/Radarr connection and Bazarr rejects weak matches; enable upgrades and it replaces previously downloaded subtitles when better ones surface. Out-of-sync files get fixed too - automatic subtitle synchronization realigns timing after download, triggered only below a configurable score threshold so good subs aren't touched. Per-show and per-movie language configuration, download history, manual on-demand search, and adaptive searching that throttles provider API calls round it out, all behind a clean Sonarr-style web UI written in Python. If your library serves multilingual viewers, this removes the last manual step.