Changing gift cards? If you just want to trade your unused gift cards, then I will suggest you check out all these sites that will buy it from you and pay you with cryptocurrency. There are lots of them, though I haven’t made use of any, you can still check them out. But if you need p2p, then you can make use of Localbitcoin.com, that’s the most popular p2p exchange and you can sell anything there and accept Bitcoin as payment, you can as well buy. Another platform you can make use of is Paxful like the other person has said,but I have not made use of paxful before. But I do check out the website sometimes and it looks good and I might be making use of it anytime. Don’t forget to do your research though.