Automate it
Sonarr, Radarr, Prowlarr: the automation stack explained without jargon
Four apps with silly names that turn a media server into something you stop maintaining. Here is what each one is for.
Updated 2026-09-01 · 4 min read
Sooner or later, adding files by hand stops being charming. You forget the new season, you download the wrong version, the subtitles are missing. The *arr stack exists to remove all of that — and its reputation for complexity comes almost entirely from nobody explaining what the pieces are.
Four apps, four jobs
| App | What it does | The one-line version |
|---|---|---|
| Prowlarr | Manages your sources and shares them with the others | The address book. Configure sources once, here, not four times. |
| Sonarr | Watches TV series | "Follow this show" — new episodes appear on their own. |
| Radarr | Same, for films | "I want this film in 1080p" — it waits until a matching version exists. |
| Bazarr | Fetches subtitles | Finds and attaches French or English subtitles automatically. |
They do not download anything themselves. They decide what to look for and hand the job to a download client (qBittorrent, or NZBGet for Usenet), then rename the result and file it where Plex or Jellyfin will find it.
How a request actually flows
- 1
You add a series in Sonarr
You pick the show and the quality you want — say 1080p, and nothing above 5 GB per episode.
- 2
Sonarr asks Prowlarr
Prowlarr queries every source you configured and returns what exists, with size, quality and seeders.
- 3
Sonarr picks and delegates
It applies your quality rules and sends the winner to the download client. If nothing matches, it waits — and checks again every few minutes, for months if needed.
- 4
The file arrives and is filed
Sonarr renames it to
Series/Season 02/Series - S02E05.mkv, moves it into the library, and tells Jellyfin to rescan. Bazarr adds subtitles. - 5
It appears on the TV
With poster, synopsis and episode number, ten minutes after the file landed. You did nothing.
Why this is the moment people rent a box
Running the stack at home means: five services to install, a download client, port configuration, keeping a machine awake so a 3 a.m. release gets caught, and updates. It is a hobby in itself.
On a managed seedbox, each of these is one click in the panel — already networked together, already pointed at the right folders, already running when you are asleep. This is the single strongest practical argument for renting rather than self-hosting.
The four mistakes of the first week
- 1Asking for the best quality of everything. "4K remux, no size limit" fills any disk in two weeks. Set a maximum size per episode from the start.
- 2Configuring sources in each app separately. That is what Prowlarr is for. Do it once there and it propagates.
- 3Not setting up the folder structure first. The apps move files; if the destination is wrong, they move them somewhere Jellyfin never looks.
- 4Monitoring entire back catalogues. Adding a 12-season series with "monitor all" queues 250 episodes at once. Monitor the current season, then go back for the rest.
+Are Radarr and Sonarr legal?
The software is, plainly: it is an open-source scheduler that queries sources you configure and renames the results. It fetches nothing on its own. Point it at Usenet providers or public-domain archives and it behaves identically. Legality lives in the sources you give it, not in the tool.
+What is the difference between Sonarr and Radarr?
Same program, different subject: Sonarr watches TV series and expects seasons and episodes; Radarr watches films and expects one file per title. Most people run both, sharing a single Prowlarr for sources and one download client.
+What does Radarr actually do?
You tell it which film you want and at what quality. It then queries your sources every few minutes — for months if needed — until a matching version exists, hands the job to the download client, renames the result properly, files it in the library, and tells Plex or Jellyfin to rescan.
+What are Lidarr and Readarr?
The same idea for music and books. Same interface, same logic. Add them only once the film and series side is stable — each app is another thing to keep configured.
+Do I need Docker?
At home, effectively yes — it is how these apps are packaged. On a managed seedbox, no: the panel installs them for you, which is a large part of the appeal.
+Does it work with Usenet as well as torrents?
Yes, and it is where the stack shines. See Usenet or torrents for what changes.
+How long until it is set up?
About an hour of clicking on a managed box, most of which is deciding your quality rules. An evening if you are installing it yourself at home.
