CronExpressionDescriptor by: Brady Holt

A library that converts cron expressions into human readable descriptions. Supports multiple languages including: English, Brazillian, Spanish, Norwgian, Turkish, Dutch, Chinese Simplified, Russian, French, German, Ukrainian, Persian (Farsi), Polish, Romanian, Italian, Swedish, Slovenian, Danish, Finnish, Greek, Kazakh, Kyrgyz and Japanese.

Dapper by: Sam Saffron Marc Gravell

A high performance Micro-ORM supporting Sql Server, MySQL, Sqlite, SqlCE, Firebird etc..

DH.NCode by: 湖北登灏科技有限公司

高性能 .NET 数据中间件（超级ORM），聚焦添删改查与海量数据，内置多级缓存、自动迁移、分表分库、强类型查询与跨库迁移。

DH.NCore by: 湖北登灏科技有限公司

Core library of NewLife framework. Provides high-performance infrastructure for building scalable applications: logging (file/network), configuration (XML/JSON/HTTP), cache (memory/distributed), network (TCP/UDP/HTTP/WebSocket), serialization (binary/XML/JSON), APM tracing, IoC container, actor model, timer scheduler, plugin framework, and more. Supports .NET Framework 4.5 to .NET 10. 核心组件库，为构建可扩展应用程序提供高性能基础设施。提供日志（文件/网络）、配置（XML/JSON/HTTP）、缓存（内存/分布式）、网络（TCP/UDP/HTTP/WebSocket）、序列化（Binary/XML/JSON）、APM性能追踪、对象容器、并行模型、定时调度、插件框架等。支持.NET Framework 4.5至.NET 10全版本。

diskann-garnet by: Microsoft

DiskANN FFI and Data Provider for Garnet

DynamicData by: Roland Pheasant

Bring the power of Rx to collections using Dynamic Data. Dynamic Data is a comprehensive caching and data manipulation solution which introduces domain centric observable collections. Linq extensions enable dynamic filtering, sorting, grouping, transforms, binding, pagination, data virtualisation, expiration, disposal management plus more.

Elasticsearch.Net by: Elasticsearch Inc. and contributors

Exposes all the api endpoints but leaves you in control of building the request and response bodies. Comes with built in cluster failover/connection pooling support.

EMGU.CV by: Emgu Corporation

Emgu CV is a cross platform .Net wrapper to the OpenCV image processing library. Allowing OpenCV functions to be called from .NET compatible languages such as C#, VB, VC++, IronPython etc.

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.

Enums.NET by: Tyler Brinkley

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

ExcelNumberFormat by: ExcelNumberFormat developers

.NET library to parse ECMA-376 number format strings and format values like Excel and other spreadsheet softwares.

Exceptionless by: Exceptionless

Exceptionless is a cloud based error reporting service that sends your exceptions to https://exceptionless.com and provides aggregated views and analytics.

Exceptionless.Portable by: Exceptionless

[DEPRECATED] Please install the Exceptionless package instead.

ExCSS by: Tyler Brinks

ExCSS is a CSS 3 parser for .NET. ExCSS makes it easy to read and parse stylesheets into a friendly object model with full LINQ support.

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

Arbitrary precision decimal class

FeatureToggle by: Jason Roberts - dontcodetired.com

An antidote to source control branching sickness for .Net developers. A simple library using the Feature Toggle design/release/continuous integration pattern

Fizzler by: Atif Aziz Colin Ramsay

Fizzler is a W3C Selectors parser and generic selector framework for document hierarchies.

FluentValidation by: Jeremy Skinner

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

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.

FSharp.Data by: Tomas Petricek Gustavo Guerra Colin Bull fsprojects contributors

The FSharp.Data package contains type providers and utilities to access common data formats (CSV, HTML, JSON and XML in your F# applications and scripts. It also contains helpers for parsing CSV, HTML and JSON files and for sending HTTP requests.