Square has released a set of developer tools for building custom, in-person checkout experiences, according to a press release. 

Square Reader SDK will enable iOS and Android developers to create unique checkout or point-of-sale applications for self-ordering kiosks, mobile points of sale, in-store line-busting apps and more on top of Square's hardware and payments ecosystem.

Square said the customized products will enable developers to work with existing Square merchants in popular industries such as retail and restaurants as well as new sellers in verticals not traditionally supported by Square, like transportation and health care. 

Nearly a dozen sellers and developers in a range of industries have already built and deployed applications that are running the SDK at scale during Square's early access program, include Shake Shack.