Gift cards can only be redeemed on the website, or by calling, or at a ticket counter location (not the app). A recent redesign of the website makes the input area hard to find. For some odd reason, Southwest now considers a gift card to be "travel funds." In the section shown above, click on "Apply Travel Funds," and it will open this box, where you can input the Gift Card: In general, Southwest Gift Cards can be problematic to use, have many limitations, and are non-refundable, so it's best to avoid them if possible. Here is the very lengthy list of Southwest Gift Card Terms for reference.
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