There are two very legitimate ways to get FREE Amazon gift cards. I'll explain them below:
1. Get an Amazon credit card. When you use your Amazon credit card on Amazon (it can be used anywhere else just like any other Visa credit card) you get extra points that you can use towards your purchase like a gift card would, or you can use to buy a gift card to send to a family member or close friend.
2. Join the Amazon Affiliates program. Do you have a website that you run where you're an expert on the topic you discuss? Why not monetize it with the Amazon Affiliate program. Whenever a reader of yours clicks on a link you recommend and purchases from Amazon, you get a small commission on the purchase. Actually, whatever that user purchases withing 24hrs of clicking your link you will get a small commission from. Remember, Amazon spends millions on testing and implementing effective advertising to keep users on their site buying more than what they originally came there for. That means more commissions for you! You can have your commissions paid out to you in the form of an Amazon gift card or by check/direct deposit (depending on what country you live in)
So there you have two very legitimate ways to get free amazon gift cards.