Top 20 NuGet mock Packages

Lightweight StandAlone Http Mocking Server for .Net.
Testing layer for Microsoft's HttpClient library
Lightweight Http Mocking Server for .Net, inspired by WireMock from the Java landscape.
ServiceFabric.Mocks contains many Mock and helper classes to facilitate and simplify unit testing of Service Fabric Actors and Services.
Utilities to streamline unit testing in Dynamics CRM 2016 by faking the IOrganizationService against an In-Memory context which runs blazingly fast.
Utilities to streamline unit testing in Dynamics CRM 365 by faking the IOrganizationService against an In-Memory context which runs blazing fast.
Utilities to streamline unit testing in Dynamics CRM 2013 by faking the IOrganizationService against an In-Memory context which runs blazingly fast.
Utilities to streamline unit testing in Dynamics CRM 2015 by faking the IOrganizationService against an In-Memory context which runs blazingly fast.
Utilities to streamline unit testing in Dynamics CRM 365 by faking the IOrganizationService against an In-Memory context which runs blazing fast.
The most powerful free mocking library available for .NET developers.
Utilities to streamline unit testing in Dynamics CRM 2011 by faking the IOrganizationService against an In-Memory context which runs blazingly fast.
Moq auto mocking integration for Stashbox.
A C# class library that handles mocking, test data generation, and validation.
Azure.Data.Wrappers Class Library
A hybrid HTTP mock library that can start both in memory server and self host server. The core facilities can make complex things possible, and the extensions can make simple things simple. Usages can be found in project test cases.
Reusable mocks that you can use to mock your database if you use Prius as your ORM.
Helper methods to work with Entity Framework 6.* and Moq libraries doing mocks of Entity Framework main methods that access database. To understand how to mock on EF 6, then what this package can do for you, give a look at: http://www.codeproject.com/Tips/1045590/Testing-with-mock-on-Entity-Framew...
Mocks of Owin Framework interfaces to use in your unit tests
FakeItEasy auto mocking integration for Stashbox.
NSubstitute auto mocking integration for Stashbox.