very good addon for firefox ! i tried many other ones and this is both simple and effective ! the drawback is that the free version is limited to 100/day that is not very sufficient...but a paid version exists if you want more. GREAT work overall !
EDIT: went from 4 stars to 1 star..after 30 days of use...i got the same message as others "
Your IP is ineligible for free credits.
Purchase a key to use with VPN/proxy."

i am not using any VPN..so its a ban....too bad !! will look for another extension that WORKS