Portable.NET

Part of the decommissionedDotGNU project, Portable.NET is a free software and open source software initiative aiming to build a portable toolchain and runtime for Common Language Infrastructure applications. The project focuses on compatibility with the ECMA-334 and ECMA-335 standards and support for .NET's base class libraries, XML, and Windows Forms. As of March 2007^[update] the latest release of Portable.NET is 0.8.0. The project supports a number of different CPU architectures and operating systems.

It was originally started by Norbert Bollow and Rhys Weatherley, at that time director of Southern Storm Software, Pty Ltd. After Rhys Weatherley and many up-to-date developers quit development of Portable.NET, Klaus Treichel, Kirill Kononenko, Radek Polak, Aleksey Demakov continued development and design of Portable.NET Just-In-Time compiler and LibJIT Just-In-Time compilation library.

Portable.NET's implementation of those components of the .NET stack not submitted to the ECMA for standardization has been the source of patent violation concerns for much of the life of the project. In particular, discussion has taken place about whether Microsoft could destroy the Portable.NET project through patent suits.

The base technologies submitted to the ECMA may be non-problematic. The concerns primarily relate to technologies developed by Microsoft on top of the .NET Framework, such as ASP.NET, ADO.NET and Windows Forms (see Non-standardized namespaces), i.e. parts composing Portable.NET's Windows compatibility stack. These technologies are today not fully implemented in Portable.NET and not required for developing Portable.NET-applications.