You exported a product CSV, edited it in Excel or Google Sheets, and uploaded it to Shopify. Shopify shows a generic error — or worse, it silently imports the wrong thing: a handle gets overwritten, a variant attaches to the wrong product, half your rows go missing. You find out days later from a customer. Shopify CSV Preflight Validator checks the file before you upload it. It runs locally on your machine, never touches your store, needs no API key, and returns three things: ...