1. Keep a previous file and a fresh copy
Retain the original supplier files. Export Excel worksheets as UTF-8 CSV rather than renaming an XLSX file. Compare two versions of the same supplier format first; a live-store export may use different price or quantity definitions.
2. Confirm the identity key
A SKU is text. Keep leading zeros and case intact. In FeedCheck, 00124 differs from 124, and abc differs from ABC. Outer whitespace is trimmed. Duplicate SKUs go to review; rows are never silently picked or quantities summed.
For multi-location inventory or repeated product rows, prepare a deliberate unique key rather than collapsing locations. Shopify describes its own SKU practices in its SKU documentation.
3. Check what the numbers actually mean
- Compare cost to cost, or selling price to selling price. They are different measures.
- Confirm currency and tax basis. A GBP-to-EUR change is not a price increase.
- Confirm units: one case of twelve is not one item.
- Choose decimal dot or decimal comma explicitly. FeedCheck accepts up to four price decimals and rejects grouping separators and currency symbols.
- Blank stock is unknown, not zero. Negative or fractional quantities need separate handling.
4. Resolve review rows before interpreting changes
Fix duplicate keys, blank SKUs and malformed numbers in a copy of the source file. Re-run the comparison. A missing SKU means absent from the new file; confirm whether the supplier discontinued it, omitted a page, or changed its code.
5. Make the review repeatable
Download the full report, including source line numbers. Save a mapping preset for the next pair of files. Presets contain column names and decimal conventions, not catalog rows.
Shopify documents common product CSV errors and its import workflow.
Setup pilot
For a supplier format whose columns, numeric conventions or exception rules are unclear, the $99 USD pilot provides one scoped setup: a reusable mapping, annotated report and repeatable instructions. A scope request comes first; fit, delivery date and payment are confirmed before work is accepted.