Residential bandwidth costs several times more than datacenter bandwidth. When that premium pays for itself, what one product page really costs to fetch, and why sourcing matters after IPIDEA.
Comparing prices is easy once you know two listings are the same product. A five-stage matching cascade, GTIN validation code, and what academic benchmarks say about accuracy.
‘3,000 results’ rarely means 3,000 reachable products. The limits we know of, where they come from, and the slicing and dedupe techniques that get you closer to the full catalog.
Before you write a single CSS selector, search the page source for the price. We checked where five big US retailers keep it, and why the first price you find is often the wrong one.
Your scraper always shops from somewhere. We checked what Walmart, Target and Amazon assumed about a visitor who never picked a store, and what that does to price data.
Fetching competitor pages is the easy 20%. This guide covers the other 80%: scope, price context, cadence, normalization, matching, quality metrics and alerts.
Most Shopify stores publish their whole catalog at /products.json. We tested 68 brand domains to measure what the endpoint really returns, where it stops, and how naive scrapers lose data.
Walmart product pages carry their price in a 500 KB __NEXT_DATA__ payload, tied to a store you may not have chosen. How to extract it, validate it and collect it without hammering the site.
Amazon is the most requested scraping target and one of the best defended. What an ASIN page actually contains, why your scraper fails, and how to tell an API error from a search cap from a block.
APIs are not always better and scraping is not always cheaper. A five-criteria comparison, a decision flow, and what changed in 2026 when Amazon retired PA-API 5.
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