NEW YORK—Earlier this year, Microsoft open sourced a big chunk of .NET, publishing its new compiler, Roslyn, and many .NET libraries under the Apache license. Today, the company took that same open sourcing effort a great deal further. Microsoft announced that its full server .NET stack, including the just-in-time compiler and runtime and the core class libraries that all .NET software depends on, will all be open sourced.

The code will be hosted on GitHub and published under a permissive MIT-style license.

With this release, Microsoft wants to make sure that the .NET stack is fully functional and production quality on both Linux and OS X. The company is working with the Mono community to make sure that this platform is "enterprise-ready."

Visual Studio is getting yet another SKU to add to its list of variants: Visual Studio 2013 Community. This is another zero-cost version of Visual Studio, sitting alongside the Express SKUs, but with a couple of important differences.

First of all, and most importantly, Community edition supports Visual Studio's extensibility system. The Express editions prohibited the use of third-party add-ins and extensions, meaning that a wide range of plugins, from alternative source control providers to Vim-style keybindings and the excellent Always Aligned elastic tabs were off-limits.

Second, there's only a single Community edition, in contrast to numerous Express editions. Instead of having different editions for Windows desktop development, Windows Phone development, Web development, and so on, Visual Studio Community will cover all the bases—just like the paid versions of the product. Longer term, Microsoft's goal is to replace the Express editions with Community, as it's a more capable product.

This version is available to hobbyists, open source developers, and small businesses with five or fewer developers. Larger development teams will still need a paid version, and companies with more than 250 staff total will only be licensed to use Community edition for open source development.

Visual Studio 2013's fourth incremental update is also available today, including a new GPU profiling tool and support for Git pull requests in Team Foundation Server.

The next iteration of Visual Studio also got a name and a preview release. It's important enough, however, that we've given it its own post.