Stockholm-based iZettle has released its first software development kit for its mobile chip-and-PIN card readers and receipt printers.

The SDK, a package of pre-written code that developers can use to add iZettle payment services to their apps, is available for iOS. iZettle said in its blog that it plans to launch an Android version later this year.

iZettle's receipt printer and combined chip-and-PIN reader and keypad connect to mobile devices via Bluetooth.

Transaction fees start at 2.75 percent and drop to 1.5 percent for monthly transactions of more than £15,000 ($24,954), iZettle said. A sliding calculator on the iZettle website allows users to calculate their monthly costs depending on the number of transactions they perform.

iZettle launched its first service in Sweden in 2011, and the company now offers its service to individuals and small businesses in Sweden, Norway, Denmark, Finland, the U.K., Germany, Spain, Mexico and Brazil.

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