Easy GIS .NET is a suite of .NET GIS mapping tools and controls to let developers easily incorporate GIS functionality into their own applications. The Desktop Edition includes a stand-alone viewing application which can be used to open and view ESRI shapefiles. This application is built using the same .NET controls that can be included in your own applications and the full source code of the application is available.
Easy GIS .NET is free software released under the Lesser General Public License. You can freely use it in personal and commercial software.
Some Notes on Performance
The library has been designed to handle very large shapefiles, without compromising performance or memory usage. For example the library is capable of opening shapefiles larger than 1GB and will not crash with OutOfMemoryExceptions like some other libraries. Easy GIS .NET will outperform almost all libraries including DotSpatial, SharpMap and even ESRI ArcObjects. If you have any doubts download the largest shapefile you can find and try and open it with Easy GIS .NET.
In 2004 while working on a GIS project, I started developing a simple .NET shapefile library using C# for in-house project purposes. At the time the company I worked for was also using ESRI products. While the library was quite good, it was shelved as my time was consumed working on other non-GIS projects. In 2007 I started working on a small project that required GIS functionality. This project did not merit investing in commercial software for the GIS functionality and so I investigated many of the Open Source and other free GIS software, only to find that they just couldn't handle large shapefiles. At this point I returned to my shapefile library and some time later the first version of Easy GIS .NET was complete.
Creator of Easy GIS .NET