Portable.ConcurrentDictionary (nuget): This is a .NET Standard 1.0, .NET 2.0, .NET 3.5, Silverlight 5.0 and Windows Phone Silverlight 8.0 & 8.1 backport from System.Collections.Concurrent.ConcurrentDictionary as defined in .NET Core
Keywords: Dictionary|ConcurrentDictionary|Collections|System.Collections.Concurrent