NWN Explorer is a Windows tool used to load game BIF files, extract files from them and in some cases display some information about them.
It is an older tool so don't expect the world from it, see the Usage tips below.
The latest versions are now on Github here: https://github.com/virusman/nwnexplorer/releases
The tool does attempt to find your installation. If it can't then direct it to the root install folder, eg it could be D:\Steam\steamapps\common\Neverwinter Nights\
The interface is generally mouse and keyboard driven, you can drill down into individual BIF (which essentially are like hakpacks but used for default game data), HAK, and override/development individual files in folders. The tool will categorise files it finds.
You can export an entire BIF or Hakpack to a folder, or an individual file out, with the right click menu. There are some issues with this:
Search is done, bizarrely, with CTRL + S as a little popup box in the bottom left. Press it again to search again. It doesn't support star search, but does do partial matches (eg; "_h.tga" finds everything ending in _h.tga, but "*.tga" won't find anything).
It can commonly crash when searching larger hakpacks (it goes through them last) or sometimes just in general - since it opens quickly it is recommended to just force close it if it hangs.
You can open several game files in the viewer - these include: