The OpenWrt project was started in 2004 after Linksys had built the firmware for their WRT54G series of wireless routers with code licensed under the GNU General Public License.[5] Under the terms of that license, Linksys was required to make the source code of its modified version available under the same license,[6][7] which enabled independent developers to create derivative versions. Support was originally limited to the WRT54G series, but has since been expanded to include many other routers and devices from many different manufacturers.