SharpDevelop (#develop) is a free and open source integrated development environment (IDE) for the .NET Framework, Mono, Gtk#, Glade# platforms. Developed by IC#Code
License: Open Source
Visual C# Express Edition is a more straightforward tool for developing Windows applications with strong Microsoft integration, while SharpDevelop is an open-source alternative that offers flexibility and support for multiple languages but lacks some of the polish and advanced features of its Microsoft counterpart.