Develop Desktop, Embedded, Mobile and WebAssembly apps with C# and XAML. The most popular .NET UI client technology

.NET Decompiler with support for PDB generation, ReadyToRun, Metadata (&more) - cross-platform!

.NET MAUI is the .NET Multi-platform App UI, a framework for building native device applications spanning mobile, tablet, and desktop.

The Roslyn .NET compiler provides C# and Visual Basic languages with rich code analysis APIs.

Open Source real-time strategy game engine for early Westwood games such as Command & Conquer: Red Alert written in C# using SDL and OpenGL. Runs on Windows, Linux, *BSD and Mac OS X.

The official repo for the design of the C# programming language

Mono open source ECMA CLI, C# and .NET implementation.

A .NET library that makes it easier to create beautiful console applications.

Cross Platform Terminal UI toolkit for .NET

Incredibly simple real-time web for .NET

The automatic type-safe REST library for .NET Core, Xamarin and .NET. Heavily inspired by Square's Retrofit library, Refit turns your REST API into a live interface.

Stride (formerly Xenko), a free and open-source cross-platform C# game engine.

C# pure functional programming framework - come and get declarative!

Extremely Fast MessagePack Serializer for C#(.NET, .NET Core, Unity, Xamarin). / msgpack.org[C#]

GraphQL for .NET

Welcome to the home of the Hot Chocolate GraphQL server for .NET, the Strawberry Shake GraphQL client for .NET and Nitro the awesome Monaco based GraphQL IDE.

Stack Exchange's Monitoring System

Extensible tool for weaving .net assemblies

Simple, powerful, cross-platform SQLite client and ORM for .NET

.NET for iOS, Mac Catalyst, macOS, and tvOS provide open-source bindings of the Apple SDKs for use with .NET managed languages such as C#

Apache Lucene.NET

Microsoft Graph Engine

A small cross-platform UI library that brings the simplicity of native UI development to the web

Collaborative chat done right

The ATF LevelEditor is a powerful tool for constructing and assembling game levels. It provides a WYSIWYG interface and allows you to place objects, edit properties, edit terrain, and build game le…

A .NET ascii/ansi console engine written in C# for MonoGame and SFML. Create your own text roguelike (or other) games!

Cross framework (WinForms/WPF/PDF/Metro/Mono/etc.), Multipurpose (UI Controls / Image generation / PDF generation / etc.), 100% managed (C#), High performance HTML Rendering library.

Render After Effects animations natively on Android, iOS, MacOS and TvOS for Xamarin

Replace any .NET method (including static and non-virtual) with a delegate

Makes things cross-platform