{
   "description": "My awesome library",
   "dependencies": {
      "NETStandard.Library": "1.6.0"
   },
   "frameworks": {
      "netstandard1.3": { }
   }
}

A library that targets netstandard1.3 can be used on any framework that supports .NET Standard 1.3 or later. Choosing a lower .NET Standard version for a library means that more projects can use it, but less APIs are available.

{
   "description": "My awesome library",
   "dependencies": { },
   "frameworks": {
      "net40": { },
      "netstandard1.3": {
         "dependencies": {
            "NETStandard.Library": "1.6.0"
         }
      }
   }
}

By targeting both net40 and netstandard1.3, the library will work in both .NET 4.0+ projects and .NET Standard projects. It's important to move the NETStandard.Library dependency into the netstandard1.3 section so it's only referenced when building for that framework.

Any project that targets netstandard1.X can be packed into a NuGet package by running:

dotnet pack

The resulting package can be uploaded to NuGet, MyGet, or hosted in a local package source.

You can specify different dependencies for each platforms:

"net45": {
    "frameworkAssemblies": {
        "System.Linq": "4.1.0"
    }
},
"netstandard1.3": {
    "dependencies": {
        "NETStandard.Library": "1.6.0",
        "System.Linq": "4.1.0-rc2"
    }
},
"netstandard1.4": {
    "dependencies": {
        "NETStandard.Library": "1.6.0",
        "System.Linq": "4.1.0"
    }
}

When this project is compiled and packed, each framework target will use a different set of dependencies:

• net45 (projects targeting .NET 4.5+) will use the System.Linq assembly from the GAC.
• netstandard1.3 (.NET Core projects targeting .NET Standard 1.3) will use the NETStandard.Library version 1.6.0 NuGet package, and the System.Linq prerelease version 4.1.0-rc2 NuGet package.
• netstandard1.4 will use the same version of NETStandard.Library, but the release 4.1.0 version of System.Linq.

If you have multiple libraries in the same solution, you can add local (project) references between them:

{
   "dependencies": {
      "NETStandard.Library": "1.6.0",
      "MyOtherLibrary": {
        "target": "project"
      }
   },
   "frameworks": {
      "netstandard1.3": { }
   }
}

The target: project property value tells NuGet to look in the current solution for MyOtherLibrary, instead of in your package sources.