Websites offering lists of redeemable free PlayStation 3 codes are scam websites that try to trick users into providing personal information. As of December 2015, Sony sells legitimate PS3 codes for up to $50.
Tricking the user by displaying fake security certificates and fake reviews from supposedly satisfied users, scam websites often demand that the user shares the website with friends to access the codes. They may then ask for personal information, including the user's phone number. The pages that demand personal information often have sales contracts written in small letters. By providing the information, the user subscribes to premium services that charge the user every month.
Moreover, even subscribing to such services does not reveal any PS3 codes. Beware of such tricks and never provide such websites with any personal information. Buy legitimate PS3 codes from Sony and other authorized vendors.