Per provider Jan 2016: This API has now been turned off. Stay tuned for the new version.
The Tesco API gives you access to the vast grocery catalog of the third-largest retailer in the world. Tesco's Grocery API has the ability to allow you to search for products using text or barcode, by dept/aisle/shelf categories, all special offers, and even previously bought 'favourites'. You can add/amend/delete items in the basket.