Square CSV validator

Square rejects an import for small reasons. A GTIN with 11 digits. A duplicate SKU. A price written as text. A missing item name. The dashboard tells you after the upload, one error at a time. This validator checks the file first. Drop it and every problem row is grouped by cause. Each group carries a count and a plain explanation of the fix. Groups that can be repaired safely have an auto-fix button. An 11 digit UPC gets its leading zero back in one click. Nothing is changed until you ask. When the list is clear, download a Square file that imports on the first try. The check runs in your browser.