File used by NuGet, an extension for Microsoft Visual Studio that provides an interface for managing third-party libraries for .NET projects; contains packaged source code that can be used for developing program components.
NUPKG files are built from .NUSPEC files, which themselves are built from .DLL assemblies.
NuGet is formally called the NuGet Package Manager. Popular NuGet packages include Microsoft Entity Framework, jQuery, and JSON libraries. You can add NuGet in Visual Studio's Extension Manager window (
NOTE: NUPKG files are compressed with Zip compression and can be extracted using a Zip utility, such as Microsoft File Explorer, 7-Zip, Apple Archive Utility, or Corel WinZip.