A cashierless store is a shop with no billing counter at all. Cameras and shelf sensors record what each shopper takes, and the shopper is charged automatically after walking out. It is also called a checkout-free store, or a just-walk-out store. Most such stores so far are small convenience shops, in offices, airports, stadiums and stations.
Here is how it works. The shopper first identifies herself at the entry gate, usually by scanning a QR code in the store's app. The app is linked to a payment method. Cameras on the ceiling then follow the shopper through the store. They do not need to recognise her face. They only need to follow the same person from the gate to the exit. Each shelf also has weight sensors. When an item is picked up, the shelf's weight falls by that item's weight. When the item is put back, the weight rises again.
The store's software combines the two. The cameras show who stood at the shelf, and the shelf shows which item left it. This uses computer vision, software that recognises objects and people in images, together with the sensor data. The cameras produce a very large amount of video. So most of the processing is done by computers inside the store, close to the cameras, rather than in a distant data centre. This is called edge AI. Similar video analytics software is used in other places, for example to count people in a building.
Imagine a small cashierless shop on an office campus in Gurugram. An employee scans the app at the gate at 4 pm. She takes a ₹40 bottle of buttermilk and a ₹60 sandwich. She picks up a ₹30 chocolate but puts it back. Then she walks out. Two minutes later, the app shows her a bill for ₹100. The store charges her saved payment method through a payment gateway. The sale is also recorded in the store's retail POS back office, like any other sale, so the stock is updated.
The difficult problems are cost and mistakes. The many cameras, shelf sensors and in-store computers cost a lot for a small shop. When several shoppers stand close together, the system can charge the wrong person. So the shopper can dispute an item in the app. Retailers weigh these costs against the cashiers they no longer need. Many stores choose a simpler step instead: a self-checkout kiosk, or scan and go on the shopper's own phone.