You can finally compare the supermarkets online prices for yourself, and it's completely free!
I built and created Save On Shopping (SoS) by myself, to help struggling families bring the cost of their food shop down. SoS is in early access so if you encounter any bugs or have any suggestions on features/design please drop me an email or contact me on Facebook through the SoS page.
When you search for a product using SoS, it will find that same product in other major supermarkets and give you the prices of each. You can create and save a shopping list, which will tell you what supermarkets are the cheapest. What's even better is, every time you open the app, the prices update so you will always be able to shop with the cheapest supermarket.
Currently I've added Tesco, Sainsburys and Asda on SoS. I'm looking to expand it to Ocado, Lidl and Aldi in the near future. I'm also working on a feature that will allow you to sync your basket in SoS with your account on the major supermarkets website, so you won't have to add everything manually to your online basket.
Please remember, this is early access and there are some parts of the app I need to iron out.
Happy saving!!