Amazon has officially opened its cashierless grocery store to the public after about a year of testing the concept with employees. 

The technology used to power the store uses a combination of computer vision and machine learning algorithms to keep track of shoppers and charge them for their selected items. Shoppers must also download the Amazon Go app before entering the store. As soon as the customer is inside, the system recognizes them as a 3D object.

The store, which is near Amazon’s Seattle headquarters, was initially slated to open in early 2017, but was postponed when the e-commerce behemoth ran into some technological difficulties. The system had issues detecting small details such as the difference between two types of yogurt or tracking groups of people rather than individuals, the Wall Street Journal reports.

While the store is cashier-free, there are still employees working to ensure operations are running smoothly and rules are being adhered to, such as checking that only those of age are purchasing alcoholic beverages, Recode reports.

Amazon has yet to announce expansion plans for its Amazon Go concept, but has confirmed the technology will not be introduced at its Whole Foods stores, according to WSJ.