Tapping the barcode scanner button top right of the shopping list will open the phone camera and detect the barcode (EAN or UPC code) on a product. If you're not in a location known to be a store this will let you add products to your shopping list.
Please note that Grosh relies heavily on crowdsourcing. For barcodes this means that the system does not know the product name in a given language before someone has scanned the barcode and entered a product name / brand for the barcode.
If a product is not found in our Grosh crowdsourced database, we use openfoodfact.org as backup. Tests have shown that it knows lots of products, has product images, brand and package size info - but often the product name is only available in e.g. French or English. However, it means that adding a scanned product to Grosh should be much simpler as most fields will be pre-filled.
When you're at a location known by Grosh to be a store, the barcode scanner button behaves a bit differently. If you scan groceries that you pick up in the store, the app will mark them as bought on the list. If no matching item is found, you can add the item to your list and mark it as bought with just one button click. Think of the barcode scanner as a different (and more detailed) way to swipe groceries on your list to mark them as bought.