1. DrunkenSlug is a popular NZB indexer that was established in 2013.
They have high retention to binary, and their APIs and NZBs both appeal on its regular and frequent downloaders.

2. DogNZB has been a top NZB site for several years because of their custom, easy to use interface with a lot of good quality content.

3. NZBPlanet is has made a mark as a popular NZB site for its premium features like built-in calendar and upcoming releases.

This Newznab-based site has a large community of members that draws good quality in its NZB forum.

4. OmgWtfNZBs is a well-developed NZB site that has been online for several years.

They are an invite-only site that indexes NZB files and has a forum feature.

5. NZBCat is an invite-only NZB site that has a more than a million files indexed in their website.

Free account members get 5 NZB grabs per day and 100 API calls.