Fresh Tomato
FreshTomato is a firmware project based on Linux, targeting home and SOHO routers. FreshTomato is distributed on the GPL license GPL license.
FreshTomato supports Broadcom based systems. I currently run Fresh Tomato firmware on two R8000 Netgear Nighthawks. It is far superior in both security and features than the original Netgear firmware that came with these routers. Unlike Netgear, updates for the router firmware to address security issues usually comes within weeks (or a month or so) of a discovered vulnerability. Netgear would take six months to over a year to address security issues, if at all.