Top 20 NuGet interfaces Packages

OS33 client API interfaces
Microsoft.VisualStudio.TextTemplating.Interfaces.15.0
Contains generic interfaces and abstract classes for sharing between ASPNetCore.PluginManager module and generic plugins
This has lots of common standard libraries like MVVM Helpers, New Collection Classes, Extensions, Exceptions, and cross platform converters.
Pre-Release of the conizi semantic models implemented in C#. Please use this library with care. It is not yet stable!
Pre-Release of the conizi semantic model core library. Please use this library with care. It is not yet stable!
Implements TestableFileSystem.Interfaces by forwarding to the .NET Framework or .NET Core.
Implements TestableFileSystem.Interfaces using a blazingly fast in-memory NTFS-based file system.
Interfaces to substitute System.IO calls in the .NET Framework and .NET Core.
Unofficial automatically-generated interfaces for the cross platform APIs exposed by Xamarin.Essentials. Suitable for mocking and for applications using dependency injection.
Loyc.Utilities contains useful non-core functionality that is either (A) not important enough to be placed in Loyc.Essentials or (B) takes Loyc.Collections, Loyc.Math or Loyc.Syntax as a dependency.
ServiceConnect Interfaces
A library of interfaces, extension methods, and small bits of functionality that are useful in almost any software project, according to the theme "things that should be built into the .NET framework, but aren’t". At least half of Loyc.Essentials is devoted to collections: collection interf...
A set of useful libraries for many kinds of .NET developers, starting with Loyc.Essentials, a library that "fills in the gaps" in the core of the .NET Base Class Library. LoycCore is especially focused on collections: classes, interfaces, adapters, and extension methods. Plus, Loyc.Syntax.dll parses...
This .NET Core library provides wrapper interfaces for the classes HttpContext, HttpRequest and HttpResponse.
An opinionated interface for REST based emails. We define minimal (simple) interfaces for request, response, and file attachements. Interfaces are defined for the client and request builder so that your implementation can be more granular if required.
Microsoft.VisualStudio.Designer.Interfaces
Contains a set of interfaces to be implemented by any logger.
Data contract interfaces.
Base application abstractions