The purpose of the ESAPI is to provide a simple interface that provides all the security functions a developer is likely to need in a clear, consistent, and easy to use way. The ESAPI architecture is very simple, just a collection of classes that encapsulate the key security operations most applications need.

http://www.owasp.org/index.php/ESAPI

View the overview presenation:

http://owasp-esapi-java.googlecode.com/files/OWASP%20ESAPI.ppt

Download the latest here:

http://owasp-esapi-java.googlecode.com/files/owasp-esapi-java-1.2.1.jar

http://owasp-esapi-java.googlecode.com/files/owasp-esapi-java-src-1.2.1.zip

The Javadoc for the project is located here:

http://owasp-esapi-java.googlecode.com/svn/trunk/javadoc/index.html

Other language version

.NET http://code.google.com/p/owasp-esapi-dotnet PHP coming soon