Torznab Indexer: A Detailed Explanation

What is a Torznab Indexer?

A Torznab indexer is a service or API that provides a standardized way to interact with torrent or Usenet indexers. It is part of the "nzb" and "torrent" search ecosystem, inspired by the NZB (Usenet) model but adapted for torrents. Torznab simplifies how applications like Sonarr, Radarr, or Prowlarr communicate with indexers by using a consistent interface.

The Torznab protocol is based on the RSS feed format and extends it with additional query parameters to enable searching, filtering, and retrieving torrent metadata efficiently.

Purpose of Torznab Indexers

Torznab indexers serve as a bridge between media management applications (like Sonarr or Radarr) and the actual torrent trackers or Usenet servers. Their key purposes include:

Centralized Management:
- Allow users to aggregate multiple torrent or Usenet indexers into a single application.
- Enable media management tools to work seamlessly with various trackers.
Standardization:
- Provide a uniform API for interacting with different indexers, which might otherwise have diverse and incompatible interfaces.
Search and Discovery:
- Enable applications to perform automated searches for specific content (e.g., movies, TV shows, or software) using criteria such as keywords, categories, or file sizes.
Automation:
- Facilitate hands-free searching and downloading of media based on predefined filters and schedules in applications like Radarr and Sonarr.

How Does a Torznab Indexer Work?

Torznab indexers work by exposing a RESTful API that supports queries and responses in a consistent format. Here's how the workflow typically looks:

1. Setup

Users configure the Torznab indexer URL and API key in their media application.
Applications send requests to the indexer using the Torznab API.

2. Request

The application makes a query to the Torznab indexer, specifying parameters such as:
- Search term: Keywords for content (e.g., a movie name).
- Category: Filters like movies, TV shows, or games.
- Limits: File size, age, etc.

Example request: GET /api?t=search&q=example_movie&cat=5000

3. Response

The Torznab indexer responds with an XML feed (based on RSS) that contains metadata about the search results.
The response includes fields like:
- Title
- Link (usually a magnet link or torrent file URL)
- Description
- Category
- Size

Example response (simplified):

<rss>
    <channel>
        <item>
            <title>Example Movie 1080p</title>
            <link>magnet:?xt=urn:btih:...</link>
            <description>Some details about the torrent.</description>
            <category>Movies</category>
            <size>2147483648</size>
        </item>
        ...
    </channel>
</rss>

Setting up as Torznab Indexer for Prowlarr

Prowlarr

Open Prowlarr, and navigate to Indexers -> Add
Search for generic, with type private
Add Generic Torznab
Give it a name at the top (Zilean)
Ensure Url is http://zilean:8181/torznab
Ensure API box is /api
Sync to Apps

Then move on to Radarr if using it

Radarr

Navigate to /settings/indexers
On Zilean click edit
Tick the Box Remove year from search string
Save

Last modified: 20 November 2024