Square and Starbucks Lead Transition to Mobile Payments. Square is the mobile payment service that lets just about any merchant accept credit or debit cards by attaching a free square-shaped credit card reader to an iPhone, iPad or Android device.

John’s Café in Palo Alto and Starbucks have two things in common. They both serve coffee and food and they let you pay for it via your cell phone.

And soon, they’ll be using the same payment system. John’s was an early adapter of Square, and Starbucks is about to adopt it big time. Square is the mobile payment service that lets just about any merchant accept credit or debit cards by attaching a free square-shaped credit card reader to an iPhone, iPad or Android device. But just as Netflix started by making it easier to rent DVDs with the goal of replacing plastic discs with downloadable movies,San Francisco-based Square is helping lead the transition away from plastic money by enabling merchants to allow customers to pay via smartphone, completely eliminating the need to swipe a credit card.