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

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

Linq to database provider.

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

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

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

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

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

An open source fork of Windows Live Writer

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.

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

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

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

Open Source Web Application Framework for ASP.NET Core. Offers an opinionated architecture to build enterprise software solutions with best practices on top of the .NET and the ASP.NET Core platforms. Provides the fundamental infrastructure, production-ready startup templates, application modules, UI themes, tooling, guides and documentation.

dotnet 7.0 API Gateway

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

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

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

One framework for creating powerful cross-platform games.

The mobile app vault (iOS and Android).

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

💫 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.

A cross-platform plotting library 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.