How Cá Buồm compares prices

Cá Buồm answers one question: where is this product cheaper today. Every number on the site is read from a public shop page and can be traced back to it with one click.

Which shops

The list grows; the current state of every source is on the data sources page.

How it works

1. 1. Read. Once a day, at night, a set of small robots opens the public category pages of each shop and records every product it sees: name, price, list price, stock status, photo and the link to the shop page. We read exactly what a customer sees; nothing is typed in by hand.
2. 2. Match. Groceries are matched by barcode (EAN), the same number printed on the pack, so a litre of the same milk from three chains becomes one product. Electronics are matched by brand and model code taken from the product name. If a shop does not give a barcode, we open the product page and read it from there. A multipack and a single unit are never merged.
3. 3. Compare. For every product we keep the lowest price, the highest price, the number of shops and the shop that is cheapest today. When a shop shows a list price above the sale price, we also record the discount.
4. 4. Remember. Each day the lowest price per shop is written to the price history. A price that has not been confirmed for 7 days is marked as out of stock and stops counting; after 30 days it is removed.
5. 5. Describe. Specifications come from the shops that publish them. Short descriptions are written by a language model from the name and specifications only, then stored; they contain no prices and no claims we cannot trace to the source.

What the badges mean

• 3 shopsthe product was found in that many shops today.
• save 12%how much cheaper the lowest price is than the highest one among the shops.
• −25%the discount the cheapest shop shows against its own list price.

What this is not

Cá Buồm does not sell anything and does not take orders. Prices are read once a day, so a shop can change a price before we notice; always check the shop page before paying. We do not track shipping fees, member prices or in-store promotions. Links to shops are plain links; no shop pays for its position.

Gold and fuel

Two boards stay from the earlier version of the site: the retail fuel price of Petrolimex, read once a day, and the SJC gold bar and plain ring price from BTMC, read every hour, with the world price converted at the Vietcombank rate.

Using the data

Figures may be quoted freely with a link to cabuom.com. Shops that want a product removed or corrected can write to us; we answer within a day.