Cecil is a library under development to generate and inspect programs and libraries in the ECMA CIL format. . In simple English, with Cecil, you can load existing managed assemblies, browse all the contained types, modify them on the fly and save back to the disk the modified assembly. . Today it is used by the Mono Debugger by the bug-finding and compliance checking tool Gendarme as well as DB4O. . http://www.mono-project.com/Cecil