IIS Express, a lightweight (4.5–6.6 MB) version of IIS, is available as a standalone freeware server and may be installed on Windows XP with Service Pack 3 and subsequent versions of Microsoft Windows. IIS 7.5 Express supports only the HTTP and HTTPS protocols. It is portable, stores its configuration on a per-user basis, does not require administrative privileges and attempts to avoid conflicting with existing web servers on the same machine. IIS Express can be downloaded separately or as a part of WebMatrix or Visual Studio 2012 and later. (In Visual Studio 2010 and earlier, web developers developing ASP.NET apps used ASP.NET Development Server, codenamed "Cassini".) By default, IIS Express only serves local traffic.