FluentValidation by: Jeremy Skinner

A validation library for .NET that uses a fluent interface to construct strongly-typed validation rules.

FakeXrmEasy by: @jordimontana

Utilities to streamline unit testing in Dynamics CRM 2011 by faking the IOrganizationService against an In-Memory context which runs blazingly fast.

FakeItEasy by: Patrik Hägne FakeItEasy contributors

It's faking amazing! The easy mocking library for .NET that works great in C# and VB.NET alike. No need to know the difference between a stub, a mock or a spy, everything's a fake! The easy to use, refactoring friendly API makes faking a breeze.

EntityFramework by: Microsoft

Entity Framework 6 (EF6) is a tried and tested object-relational mapper for .NET with many years of feature development and stabilization.

FirebaseAdmin by: Google Inc.

Firebase Admin SDK enables server-side .NET developers to integrate Firebase into their services and applications.

DotNetOpenAuth.OpenId.RelyingParty by: Andrew Arnott

Increase conversion rates to your web site by lowering the bar to create an account with your site, by allowing customers to use accounts they already have with other sites, such as Google and Yahoo!

FluentFTP by: Robin Rodricks FluentFTP Contributors

An FTP and FTPS client for .NET & .NET Standard, optimized for speed. Provides extensive FTP commands, File uploads/downloads, SSL/TLS connections, Directory listing parsing, File hashing/checksums, File permissions/CHMOD, FTP proxies, FXP transfers, UTF-8 support, Async/await support, Powershell support and more. Written entirely in C#, with no external dependencies.

FakeXrmEasy.365 by: @jordimontana

Utilities to streamline unit testing in Dynamics CRM 365 by faking the IOrganizationService against an In-Memory context which runs blazing fast.

Fare by: Nikos Baxevanis

.NET port of dk.brics.automaton - Project Fare is an effort to bring a DFA/NFA (finite-state automata) implementation from Java to .NET. There are quite a few implementations available in other languages today. This project aims to fill the gap in .NET.

FluentAssertions by: Dennis Doomen Jonas Nyrup

A very extensive set of extension methods that allow you to more naturally specify the expected outcome of a TDD or BDD-style unit tests. Targets .NET Framework 4.5 and 4.7, as well as .NET Core 2.0, .NET Core 3.0, .NET Core 2.1, .NET Standard 1.3, 1.6, 2.0 and 2.1. Supports the unit test frameworks MSTest, MSTest2, Gallio, NUnit, XUnit, MBUnit, MSpec, and NSpec.

DotNetOpenAuth.OpenId.Core by: Andrew Arnott

This package contains shared code for other NuGet packages, and contains no public API in and of itself.

DotNetOpenAuth.OAuth.Core by: Andrew Arnott

This package contains shared code for other NuGet packages, and contains no public API in and of itself.

FluentValidation.AspNetCore by: Jeremy Skinner

AspNetCore integration for FluentValidation

FluentScheduler by: Jim Geurts <jim@biacreations.com> Talles L <talleslasmar@gmail.com> & further contributors

Automated job scheduler with fluent interface.

ExtendedNumerics.BigDecimal by: https://github.com/AdamWhiteHat

Arbitrary precision decimal class

font-awesome by: Dave Gandy

Font Awesome gives you scalable vector icons that can instantly be customized — size, color, drop shadow, and anything that can be done with the power of CSS.

Enums.NET by: Tyler Brinkley

Enums.NET is a high-performance type-safe .NET enum utility library

Dynamitey by: Dynamitey

(pronounced dyna-mighty) flexes DLR muscle to do meta-mazing things in .net

DotNetZip by: Dino Chiesa

DotNetZip is an easy-to-use, FAST, FREE class library and toolset for manipulating zip files or folders.

FsUnit by: Ray Vernagus Daniel Mohl Sergey Tihon Constantin Tews

FsUnit is a set of extensions that add special testing syntax to NUnit.