Find it cheaper / about
You paste the link to something you are about to buy. This works out exactly what the product is, goes looking for other sellers of the same thing, and shows you only the ones that cost less.
The pasted page is read first, for its title, brand, product id and price. Plenty of large retailers will not give any of that to a crawler, so the product is identified from the words in the URL instead, which is usually enough.
Claude turns that into a few plain search queries, the way a person would type them, and the shopping results for those queries are pulled in. Offers that already cost more than your link are dropped on the spot. What is left goes back to Claude with one job: keep only the offers that are the same product and cost less, and say why for each one. Everything rejected is listed at the bottom of the page with its reason, so you can see what was thrown away and disagree.
A different capacity, a different generation, a two pack, a bundle with extras, an accessory or a renewed unit sold as new are all different products. A different size or colour of the same garment is not: that one is kept, and the size is shown on the card so you can filter to yours.
Where a seller publishes a product id, that id is read off their own page and held against your link's. An offer carrying the same id is marked "Same product id", which is the difference between a title that claims to match and one that proves it. Many retailers refuse to be read, so most offers carry no mark either way.
Everything depends on getting that one number right, so it comes in order of trust: what you typed, then what the page published, then that same retailer's own listing in the search results. If all three fail, you are asked for it rather than guessed at. When the source retailer turns out to be selling it for less than the price first read, the lower number wins and the savings are recalculated.
No link on this site earns a commission, no seller can pay to appear, and nothing is ranked by anything except price. Marketplace and no name sellers do turn up in the results; where one looks risky it is flagged on the card, but the judgement is still yours.
Prices change constantly. A saved comparison is a record of one moment, and the date it was checked is at the bottom of every page.