You can apply coupons/credits at checkout on a computer or with the StubHub app. 

On a computer, at checkout's 'Review and Buy' page:

1. After adding a payment method:
   • You have existing coupons/credits: Under 'Discount Codes,' check the coupon/credit you want to apply to your order
   • To add one: Select 'Manage discounts,' followed by '+ ADD A DISCOUNT CODE' and type in the gift card number to apply to your order. Then select 'Add.'
     
2. Check the box next to the applicable code. Select 'Apply.'

On the StubHub app, at checkout's 'Review and Buy' page: 

1. After adding a payment method, select 'Manage Discounts'
   • You have existing coupons/credits: Select the ones you want to apply to your order
     
   • To add one: Select '+ ADD A DISCOUNT CODE' enter the number, and 'Add'
2. Check the box next to the applicable code and select 'Apply'