nzbdump is a free tool that displays the contents of an NZB file. Nzbdump is not a newsreader or downloader, and cannot download files for you. It's main a diagnostic tool that you might be able to use if you're having trouble with an NZB file.
Nzbval is a free utility that you can use you test an NZB file against your news server and verify that all of the parts exist before you start downloading. It can save you a lot of time because you can avoid downloading from bad .NZB files.
Nzbedit is a free GUI editor designed to let you edit the contents of an NZB file. You can change the fields of the NZB including the subject an author fields. ...