SABnzbd: Usenet Download Automation
SABnzbd downloads from Usenet: give it an NZB file and it fetches the articles, repairs anything corrupt, unpacks the result, and files it.
What it actually automates
Usenet retrieval involves fetching thousands of article segments, verifying them, using par2 parity files to repair missing pieces, then extracting a multi-part archive. Doing that manually is unthinkable; SABnzbd makes it invisible. You never see the intermediate steps unless something fails.
Why Usenet rather than torrents
Downloads come from your provider’s servers at full line speed rather than depending on peers, there is no seeding obligation, and connections are TLS-encrypted to the provider. The costs are real though: Usenet requires a paid provider subscription and usually a separate indexer subscription, where public torrent trackers are free. Retention is finite, so older content eventually disappears.
Integration
Sonarr, Radarr, and the rest of the *arr family drive SABnzbd through its API, with categories mapping to save paths so completed downloads land where the automation expects them. Prowlarr manages indexers centrally.
Configuration worth getting right
Set the number of connections to what your provider allows rather than the maximum possible. Keep incomplete and complete directories on the same filesystem to avoid a slow copy at the end of every download, and ideally on the same filesystem as your media library so hardlinks work.
Alternatives
NZBGet does the same job in C++ with a smaller footprint, which is the usual choice on constrained hardware.
License
SABnzbd is released under the GNU General Public License v2.0.