The .NET ESAPI project is a complete rewrite of the Java-based ESAPI Project to the .NET platform.
The goal of the project is to maintain an API and reference library for ASP.NET developers who want to create secure applications. While this is a complete translation of the API, there are some minor differences between the original ESAPI and the .NET ESAPI.
To download and work with the source you must use an SVN tool.
AnkhSVN is a free SVN tool that integrates with Visual Studio.
You can also browse the source.
The project lead is Alex Smolen.