OpenAPI (f.k.a Swagger) Specification code generator. Supports C#, Go, Java, Node.js, TypeScript, Python, Ruby and PHP. 

AutoRest is an open source tool that generates client libraries for accessing RESTful web services. 

Video Tutorial : https://azure.microsoft.com/en-us/resources/videos/inside-autorest-with-david-justice/ 

C4 is an open-source creative coding framework that harnesses the power of native iOS programming with a simplified API that gets you working with media right away. Build artworks, design interfaces and explore new possibilities working with media and interaction

Covalent is a reusable UI platform from Teradata for building web applications with common standards and tooling. It is based on Angular and Material Design.

Vision: To build an atomic, reusable component platform for Teradata to consume, while collaborating in an open source model. 

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ReactOS is an open source alternative to the Windows operation system. Even if the first version of ReactOS dates back to 1998, there is still no 'stable' version of ReactOS. May be, the most important reason is a lack of attention

Redis (REmote DIctionay Server) is a very popular open-source, networked, in-memory, key-value data store, sometimes referred to as a data structure server which also comes with optional durability. Redis is well known for high performance, flexibility, provides a rich set of data structures, and a simple straightforward API.  

R is decidedly the most popular statistical/data analysis language in use today. R Tools for Visual Studio brings together the power of R and Visual Studio in a convenient and easy to use plug-in that’s free and Open Source 

Spark is an open source computing framework for Big Data, and it’s becoming increasingly popular, especially in machine learning scenarios. In this article I’ll describe how to install Spark on a machine running a Windows OS, and explain basic Spark functionality from a .NET developer’s point of view. 

 The claims for JET are: Complete JavaScript development toolkit, Leverages popular open-source technologies, Full lifecycle management for template based SPA, Built in accessibility support, Support for internationalization (28 languages and 160+ locales)Rich set of UI components, Advanced two-way binding with a common model layer, Powerful routing system supporting single-page application navigation, Smart resource management

".NET Fringe is a new conference focused on .NET developers who are breaking the rules and pushing the boundaries. The .NET platform is more interesting today than it ever has been! The old Microsoft that was at odds with Open Source has been replaced with on

Node.js Tools 1.0 for Visual Studio (NTVS) is now available for download! NTVS is a free, open source extension for Visual Studio 2012 and Visual Studio 2013 that turns Visual Studio into a Node.js IDE. NTVS 1.0 supports the free Visual Studio Community and Visual Studio Express for Web editions, as well as Visual Studio Professional and higher