A number of tools have been created by independent software vendors which provide the ability for Windows Updates to be automatically downloaded for, or added to, an online or offline system. One common use for offline updates is to ensure a system is fully patched against security vulnerabilities before being connected to the Internet or another network. A second use is that downloads can be very large, but may be dependent on a slow or unreliable network connection, or the same updates may be needed for more than one machine. AutoPatcher, WSUS Offline Update, PortableUpdate, and Windows Updates Downloader are examples of such tools.