Amazon issue plastic gift cards, online e-mail gift vouchers, and print-at-home gift vouchers. All Amazon gift cards and vouchers are valid 10 years from purchase, and must be redeemed in full into an online account. Once redeemed, it is not possible to transfer funds to another account. Amazon is a prolific gift card issuer and encourages third parties to promote them, so you could receive Amazon gift vouchers as rewards from other shops and businesses. Amazon gift cards are very popular and tend to hold their value.
Amazon no longer provide a balance checker, but if you have any doubts about your gift card you can contact their excellent customer centric customer services by chat and they will answer your query.