FastExpressionCompiler.src by: Maksim Volkau

FastExpressionCompiler is 10-40x times faster than Expression.Compile()

FastMember by: Marc Gravell

In .NET reflection is slow... well, kinda slow. If you need access to the members of an arbitrary type, with the type and member-names known only at runtime - then it is frankly hard (especially for DLR types). This library makes such access easy and fast.

FastMember.Signed by: Marc Gravell

In .NET reflection is slow... well, kinda slow. If you need access to the members of an arbitrary type, with the type and member-names known only at runtime - then it is frankly hard (especially for DLR types). This library makes such access easy and fast.

FirebirdSql.Data.FirebirdClient by: FirebirdSQL

Firebird ADO.NET data provider

Fleck by: statenjason

C# WebSocket Implementation

FluentAssertions by: Dennis Doomen Jonas Nyrup Xceed

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. Works with .NET Standard 2.0 and higher, .NET Framework 4.7 and higher and .NET 6 and higher. Supports the unit test frameworks MSTest2, NUnit3, NUnit4, XUnit2, XUnit3, MSpec and TUnit. IMPORTANT: This version is free for open-source projects and non-commercial use, but commercial use requires [a paid license](https://xceed.com/products/unit-testing/fluent-assertions/). Check out the [license page](LICENSE) for more information.

FluentEmail.Core by: Luke Lowrey Ben Cull Github Contributors

Send emails very easily. Use razor templates, smtp, embedded files, all without hassle. This is a Base Package and includes just the domain model, very basic defaults, and is also included with every other Fluent Email package here.

FluentEmail.Smtp by: Luke Lowrey Ben Cull Github Contributors

Now we're talking. Send emails via SMTP. At the moment, only works on .NET 4.

FluentNHibernate by: James Gregory and contributors

Fluent, XML-less, compile safe, automated, convention-based mappings for NHibernate.

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

Automated job scheduler with fluent interface.

FluentValidation by: Jeremy Skinner

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

FluentValidation.AspNetCore by: Jeremy Skinner

AspNetCore integration for FluentValidation

Fluid.Core by: Sebastien Ros

Fluid is a template engine based on the Liquid markup, with focus on performance and .NET programming patterns.

Flurl by: Todd Menier

A fluent, portable URL builder. To make HTTP calls off the fluent chain, check out Flurl.Http.

Flurl.Http by: Todd Menier

A fluent, portable, testable HTTP client library.

Fody by: The Fody Team

Extensible tool for weaving .net assemblies.

FParsec by: Stephan Tolksdorf

FParsec is a parser combinator library for F#. You can find comprehensive documentation for FParsec at http://www.quanttec.com/fparsec. The documentation includes a feature list, a tutorial, a user’s guide and an API reference. This package uses the basic “low-trust” configuration of FParsec, which does not use any unverifiable code and is optimized for maximum portability. If you need to parse very large files or if you employ FParsec for performance-critical jobs, consider using the alternate “Big Data Edition” NuGet package (see https://nuget.org/packages/fparsec-big-data-edition).

Fractions by: Daniel Mueller

The fraction data type consists of two BigInteger values for numerator and denominator. It implements various operations (addition, subtraction, multiplication, division and remainder) with operator overloads.

FreeRedis by: FreeRedis

FreeRedis is .NET redis client, supports cluster, sentinel, master-slave, pipeline, transaction and connection pool.

FreeSql by: FreeSql ncc YeXiangQin

FreeSql is the ORM in .NetCore, .NetFramework, And Xamarin. It supports Mysql, Postgresql, SqlServer, Oracle, Sqlite, Firebird, Clickhouse, DuckDB, TDengine, QuestDB, Odbc, Oledb, 达梦, 人大金仓, 南大通用, 虚谷, 神舟通用, 翰高, And Access