These files can be placed underneath the Prowlarr appdata directory Prowlarr→System→Status→AppData directory inside the Definitions/Custom folder in order to add onion websites for indexers that provide a service over tor.

For example, in order to add the The Pirate Bay onion address as an indexer:

• In Prowlarr, navigate the menu to System→Status and check the location of the appdata directory (ie: /var/lib/prowlarr),
• Using a shell, create the directory Definitions/Custom under the appdata directory (ie: /var/lib/prowlarr/Definitions/Custom).
• Place one of the files provided (in this example, the thepiratebayonion.yml file) inside the created directory and name it tpbonion.yml (ie: /var/lib/prowlarr/Definitions/Custom/tpbonion.yml):
• Prowlarr automatically reloads the definitions but to be safe, restart Prowlarr (ie: systemctl restart prowlarr) and then go to the Indexers menu item once it has started,
• Click Add Indexer and then look for the indexer The Pirate Bay (Onion) and add it to the list,
• Make sure that the proxy tag is added to the Tags field on the indexer configuration screen,
• Click Test and then Save.

In order for the indexer to be synchronized to all configured apps, a forced re(synchronization) can be triggered from the Prowlarr task schedule page.