Methodology

1. How we match products

The hard part of price comparison is knowing that "Sony WH-1000XM5" at one retailer is the same product as at another. We match in tiers, most reliable first:

• Barcode (highest confidence). We match on the product's global barcode — GTIN-13, EAN, UPC, or ISBN — normalising check digits. Categories with clean barcodes (electronics, games, books, appliances) are where we start.
• Brand + manufacturer part number (MPN). When no barcode is available, we match on brand plus the manufacturer's part number.
• Guarded title similarity (last resort). If neither is available, we compare brand and title with a similarity score. Below a confidence threshold we do not merge the listings — we'd rather keep two products separate than wrongly merge them.

We never merge different variants (a different size, colour, or capacity is a different product). Every match records a confidence score and method for auditing.

2. When a product gets a comparison page

We only publish a comparison when there are at least 3 offers from at least 2 different retailers for the same matched product in United Kingdom. Below that, a "comparison" would be misleading, so we don't show one.

3. How we rank offers

Within a product page, offers are sorted cheapest first for United Kingdom in GBP. Ranking is based on price and objective factors such as stock status and shipping — never on how much commission a retailer pays us (see how we make money).

4. Region correctness

Prices are always compared within a single region. We never place a US-dollar price next to a British-pound price in the same table, because shipping, duties, and currency make that comparison misleading. You're viewing United Kingdom (GBP).

5. How fresh our prices are

Retailer prices and stock change constantly. We re-pull retailer feeds on a schedule and stamp every price with an "as of" time. Offers that are older than our freshness window are hidden rather than shown stale. Amazon prices are fetched live from Amazon's API. Always confirm the final price on the retailer's site before buying.

6. Corrections

If you spot a wrong match or a stale price, tell us on the contact page and we'll fix it.