Open Source applications provide alternatives to commercial software that fill needs not met by paid options. Some key open source applications include GNU/Linux, which was completed by Linus Torvalds' kernel in 1992; SourceForge, a portal for developing and distributing open source software; and Firefox, one of the first successful open source browsers and current market leader. These and other open source tools like FreeNAS, Gparted, Clonezilla, and VLC Media Player offer free and customizable alternatives to proprietary software.