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Indexers

Search engines for your media. Where the arr apps actually find content.

What are indexers?

Indexers are like search engines -- but instead of searching the web, they search Usenet and torrent networks. They crawl, catalog, and organize available content into searchable databases. When Sonarr searches for "Breaking Bad S01E01," the indexer is what finds matching results and returns them.

Without indexers, your arr apps are blind. They're the most important piece of the puzzle after the apps themselves.

There are two types, matching the two download methods:

Usenet indexers

Usenet indexers scan the binary newsgroups, identify what's been posted, and create searchable entries with NZB files. Think of them as librarians who organize the chaos of Usenet into something you can actually search.

How they work

An indexer constantly monitors Usenet newsgroups. When it detects a new post (or set of related posts that make up a file), it:

  1. Identifies what the content is (movie, TV episode, album, etc.)
  2. Catalogs it with metadata (title, year, quality, size)
  3. Generates an NZB file that your download client can use to retrieve it
  4. Makes it searchable via their website and API

The arr apps talk to indexers via their APIs -- the whole process is automatic. You never need to visit the indexer's website manually (though you can for browsing).

Types of Usenet indexers

Notable Usenet indexers

Use multiple indexers. No single indexer has everything. Running 2-3 indexers significantly improves your hit rate. The arr apps search all configured indexers simultaneously and pick the best result.

Torrent indexers and trackers

Torrent indexers (also called trackers or sites) catalog torrent files. They come in two flavors:

Public trackers

Anyone can access these without an account. They index publicly available torrents.

Private trackers

Members-only sites with strict rules. You typically need an invitation to join.

Some well-known private tracker communities (without naming specific sites):

Getting into private trackers

The most common paths:

  1. Open signups: Some trackers periodically open registration. Follow communities that announce these (Reddit, various forums).
  2. Interviews: Some trackers have IRC-based interviews where you demonstrate knowledge of torrenting etiquette, audio formats, etc.
  3. Invites: Existing members can invite new users. Build a good reputation on one tracker and invites to others often follow.
  4. Recruitment threads: Some trackers recruit from other trackers. If you have a good ratio and account age on one site, others may recruit you.
Start with public trackers. They're perfectly fine for getting started. Private trackers are nice to have but not required. You can build a great media library with just public trackers and a couple of Usenet indexers.

Prowlarr: managing it all

If you've read the *Arr Stack guide, you already know about Prowlarr. It's the centralized indexer manager -- you add all your indexers to Prowlarr once, and it syncs them to all your arr apps automatically.

Docker setup

If you haven't already set up Prowlarr (it was included in the arr stack docker-compose):

services:
  prowlarr:
    image: lscr.io/linuxserver/prowlarr:latest
    container_name: prowlarr
    environment:
      - PUID=1000
      - PGID=1000
      - TZ=America/New_York
    volumes:
      - ./prowlarr/config:/config
    ports:
      - "9696:9696"
    restart: unless-stopped

Adding indexers to Prowlarr

  1. Open Prowlarr at http://your-server:9696
  2. Go to Indexers > Add Indexer
  3. Browse or search the list -- Prowlarr supports hundreds of indexers out of the box
  4. Select your indexer and fill in the required credentials:
    • Usenet indexers typically need an API key (found in your account settings on the indexer's website)
    • Public torrent trackers usually need no credentials
    • Private trackers need your cookie, API key, or passkey depending on the site
  5. Click "Test" to verify the connection works
  6. Click "Save"

Syncing indexers to your apps

Go to Settings > Apps and add each arr app you want indexers synced to:

  1. Click "Add Application"
  2. Select Sonarr/Radarr/Lidarr/Readarr
  3. Set the sync level to Full Sync (Prowlarr manages all indexers in the app)
  4. Enter the Prowlarr server URL: http://prowlarr:9696
  5. Enter the app's URL: e.g., http://sonarr:8989
  6. Enter the app's API key (found under Settings > General in each app)
  7. Test and save

Now all your indexers automatically appear in Sonarr, Radarr, etc. Add or remove an indexer from Prowlarr and it updates everywhere.

Sync profiles

By default, Prowlarr syncs all indexers to all apps. But you might want more control:

You can create custom sync profiles under Settings > Apps and assign them per indexer. This keeps your apps from searching irrelevant sources.

Jackett: the older alternative

Jackett was the original indexer proxy before Prowlarr existed. It translates torrent tracker searches into a standardized API that the arr apps can use. It's still actively maintained and works fine.

However, Prowlarr is generally recommended over Jackett for new setups because:

If you're already using Jackett and it works, there's no urgent need to switch. But for new setups, go with Prowlarr.

Tips for better results

More indexers = better results

Run at least 2-3 indexers across different sources. A mix of Usenet and torrent indexers gives you the best coverage. The arr apps search all of them in parallel.

API limits

Most indexers limit how many API calls you can make per day. Free tiers might cap you at 5-25 searches per day. Paid tiers are usually 100+ or unlimited. If your arr apps are showing "indexer unavailable" errors, you might be hitting API limits.

Keep your indexer accounts active

Some indexers purge inactive accounts after 6-12 months. Log in occasionally to keep your account alive, especially invite-only indexers that are hard to get back into.

RSS feeds

The arr apps periodically check indexer RSS feeds for new content. This is how they discover new episodes or movies as they become available, without doing a full search every time. Make sure RSS is enabled for your indexers in Prowlarr.

Next steps

You've got your indexers set up and feeding content to your arr apps. The last piece is giving users a way to request content -- head to the Overseerr & Jellyseerr guide to set up a beautiful request system.