Hollis Johnson
The chain is offering the food to promote its new app, called Chick-fil-A One, which launched on Wednesday.
Anyone who downloads the app between June 1 and June 11 will get their choice of a free original, spicy, or grilled chicken sandwich, the company told Business Insider.
The offer must be redeemed by June 30.
Going forward, Chick-fil-A plans to offer even more free food through its app.
The app has a built-in rewards program that will send customers free-food offers based on what they typically order.
"We want to surprise customers with items they love the most," said Michael Lage, Chick-fil-A's senior manager of digital experience.
When customers get free treats from Chick-fil-A, they will have the opportunity to rate them. Those ratings will be factored into the app's future free-food offers.
Customers will typically get a choice of several items for their free-food offers. For example, they will be allowed to choose among a free drink, dessert, or medium fry.
"We want to make sure the experience is based on personalization and choice," Lage said.