Command line parsing, invocation, and rendering of terminal output.

The mobile app vault (iOS and Android).

One framework for creating powerful cross-platform games.

Build Mobile, Desktop and WebAssembly apps with C# and XAML. Today. Open source and professionally supported.

ASP.NET Core is a cross-platform .NET framework for building modern cloud-based web applications on Windows, Mac, or Linux.

.NET core API Gateway

Highly performant and modular controls for node-based editors designed for data-binding and MVVM.

Accept Bitcoin payments. Free, open-source & self-hosted, Bitcoin payment processor.

:cake: Cake (C# Make) is a cross platform build automation system.

Lean Algorithmic Trading Engine by QuantConnect (Python, C#)

A cross-platform plotting library for .NET

xUnit.net is a free, open source, community-focused unit testing tool for .NET.

💫 NClient is an automatic type-safe .Net HTTP client that allows you to call web service API methods using annotated interfaces or controllers without boilerplate code.

.NET for Apache® Spark™ makes Apache Spark™ easily accessible to .NET developers.

AutoFixture is an open source library for .NET designed to minimize the 'Arrange' phase of your unit tests in order to maximize maintainability. Its primary goal is to allow developers to focus on what is being tested rather than how to setup the test scenario, by making it easier to create object graphs containing test data.

A wrapper executable that can run any executable as a Windows service, in a permissive license.

ML.NET is an open source and cross-platform machine learning framework for .NET.

Powerful .NET library for benchmarking

EF Core is a modern object-database mapper for .NET. It supports LINQ queries, change tracking, updates, and schema migrations.

An open source fork of Windows Live Writer

Open Source Web Application Framework for ASP.NET Core

Every programmer needs a rubberduck. COM add-in for the VBA & VB6 IDE (VBE).

The best C# command line parser that brings standardized *nix getopt style, for .NET. Includes F# support

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

Linq to database provider.

Google's Material Design in XAML & WPF, for C# & VB.Net.