SharpDevelop is a free IDE for C# and VB.NET projects on Microsoft's .NET platform. Its features forms designer for C# and VB.NET, code completion for C# and VB.NET (including Ctrl+Space support), XML editing; folding, code auto insert (Alt+Ins), C# to VB.NET converter, as well as VB.NET to C# converter; completely written in C#; compile C# and VB.NET in the IDE out-of-the-box, open source, ILAsm and C++ backends, integrated NUnit support, assembly analyzer, and XML documentation preview. You can add new project or file types, or even compilers to SharpDevelop.
SharpDevelop Portable 5.1 Rev. 2