FxCop (Framework Police) is a free code analysis tool provided by Microsoft basically intended for class library developers. It is a must have tool for new developers who want help in getting familiarized with Microsoft Design Guidelines. FxCop helps to write robust code and easily maintain code by telling you about the possible design, localization, performance and security improvements. It can prevent flaws in the code and helps the programmer to follow best practices. FxCop is fully integrated in the Visual Studio and is distributed as both a fully featured application that has a graphical user interface (FxCop.exe) for interactive work, and a command-line tool (FxCopCmd.exe) suited for use as part of automated build processes or integrated with Microsoft Visual Studio® .NET as an external tool. It analyses Binary Common Intermediate Language (CIL) instead of the source code, it is not language specific tool and can be used for analysing a dll written in any programming language.