Wendy's isn't the only chain cashing in on the National Hamburger Day promotions. At Burger King on May 28, Royal Perks loyalty program members can get a free hamburger with a purchase of $1 or more.

Wednesday, May 28, is National Hamburger Day, giving burger chains an excuse to offer their customers some deals. Most deals are for loyalty members, but several include cheese on the burgers.

You can tack on a one-cent Jr. Bacon Cheeseburger to any in-app purchase, from National Hamburger Day on May 28 to June 1. Customers should register for a Wendy's rewards account to claim the deal.