A small number of Shopify storefronts - usually due to caching or theme configuration - don’t honor the page parameter on /products.json at all, and return the exact same first page no matter what number you request. A naive script that keeps incrementing page expecting new data will loop until it hits whatever ceiling it was given, downloading duplicates the whole way.

This tool checks for that specifically: it compares the first product on each new page against the first product on the previous one, and if they match, it stops immediately and reports why, instead of grinding through 200 pages of the same 250 products.

You still get every unique product the store returned before it started repeating - just without the wasted requests or duplicate rows.

This tends to show up most on smaller or older storefronts, sometimes due to aggressive page-level caching rather than anything actually wrong with the catalog itself. Either way, the fix lives entirely on this end - there’s nothing to configure or troubleshoot on the store’s side to work around it yourself.