Hardware & SDK Engineering: Design, build, and maintain modular native iOS SDKs and frameworks that communicate with Bluetooth Low Energy (BLE) card readers, smart accessories, and next-generation terminal hardware. Card Reader & Payment Experience: Any prior experience working with payment processors, card readers (e.g., Clover, Square, Stripe Terminal, Ingenico, Verifone), or point-of-sale (POS) systems is highly valued .