May is National Hamburger Month and Burger 21, an award-winning, “beyond the better burger” fast-casual franchise, is paying tribute to one of the greatest staples of American cuisine by rewarding guests who download its “B Loyal” mobile app with a free Cheesy Burger offer. One lucky fan also will win free Cheesy Burgers for a year on National Hamburger Day, May 28.

Now through May 27, guests are encouraged to download Burger 21’s free mobile app and register in order to receive an offer for a free Cheesy Burger and automatically be entered for a chance to win free Cheesy Burgers for a year. The winner will be randomly selected and announced on National Hamburger Day, May 28. The app is available for download at the Apple App Store or Google Play. Guests can earn a $5 reward for every seven visits to a Burger 21 restaurant.

“At Burger 21, we consider ourselves to be the master of the burger and our menu of 10 beef and 10 non-beef options, in addition to a rotating monthly featured burger, speaks for itself,” says Mark Johnston, president and founder of Burger 21. “We know that there are many people who feel as passionately as we do about a great burger, so in honor of National Hamburger Month, we want to give one lucky guest a chance to enjoy free Cheesy Burgers for a year.”

As part of its unique culture, Burger 21 offers a different chef-inspired burger and handcrafted shake on the 21st of every month. In addition, the brand donates 10 percent of its restaurants’ sales to a local charity or school in the communities it serves on this day.