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

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

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.

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

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

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

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

Mutation testing for .NET core and .NET framework!

Open-source platform for building cross-platform native Mobile, Web, Desktop and Embedded apps quickly. Create rich, C#/XAML, single-codebase apps from any IDE. Hot Reload included! 90m+ NuGet Downloads!!

One framework for creating powerful cross-platform games.

This repository contains a suite of libraries that provide facilities commonly needed when creating production-ready applications.

Linq to database provider.

Headless Chrome .NET API

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

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

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

Microsoft PowerToys is a collection of utilities that supercharge productivity and customization on Windows

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

Powerful .NET library for benchmarking

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

.NET API Gateway

An open source fork of Windows Live Writer

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