I mean -- the websites you are visiting are bound to be using non-free proprietary software. At least a few of them.

Actually -- the routers your packets travel through are using proprietary non-free software!

The BIOS that boots your PC is non-free and proprietary!

Just throw your computer out -- that is the only sure way to stop using non-free software. (actually, don't throw it out -- just mail it to me ;)