Amazon is testing a grocery store model in the US city of Seattle which works without checkouts.

Shoppers scan an app when they go in, and then anything they pick up and put in their bag is detected by sensors and added to your virtual cart.

When you walk out, the scanning technology gives you a total bill.

If you put an item back you don't pay.

The store is testing for Amazon employees initially, but is expected to open to the public early next year.