How do I use the Coupons at Checkout Mobile Safari Extension?
During checkout on any supported e-commerce website, you can tap "Find Coupons". A list of coupons will automatically appear that you can use in just four taps.

As shown above, just following four simply steps:
1. Tap the Share button

2. Tap Find Coupons to confirm setup

3. Tap a coupon from the list
4. Apply the coupon to your shopping cart.
Coupons that are greyed out have expired or been reported as no longer valid. Coupons with a green indicator have recently worked for other users.