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Free tool · runs in the browser

Duplicate SKU checker

Inventory sync matches products by SKU. Two products with the same SKU, or SKUs that differ only by a space or letter case, make the match fail or hit the wrong product. Paste a list and see the conflicts.

Paste SKUs, one per lineFree

The example list below contains three conflicts. Replace it with your own.

Runs in the browser. Nothing is uploaded.

What it checks

  • Exact duplicates: the same SKU on two or more lines.
  • Same SKU after trim and case: CANDLE-CEDAR and candle-cedar. Some systems treat these as one SKU, others as two, so a sync can match the wrong product.
  • Leading or trailing spaces: SOCKS-WOOL-M with a space at the end looks identical on screen but does not match.

Empty lines are ignored. Line numbers in the results refer to the pasted list, so they map back to rows in your export.

Get the SKU list

Square

Square Dashboard → Items & services → Items → Actions → Export library. Open the file and copy the SKU column. Each variation has its own SKU.

WooCommerce

WP Admin → Products → Export. Include variations. Copy the SKU column; variable products list the parent and each variation on separate rows.

Zettle

Zettle back office → Products → Export products to a spreadsheet, then copy the SKU column.

To check both sides together, paste the Square or Zettle list and the WooCommerce list one after the other. Every matched product then shows up as a duplicate, which is expected; look for the near-duplicates and spaces.

Reading the results

An exact duplicate inside one system is always a problem: the sync can't tell which product a stock change belongs to. A case or spacing variant across two systems means the products won't be matched at all, so stock stays out of sync without any error.

Fixing conflicts

  1. Pick one format for SKUs, for example upper case with hyphens, and no spaces.
  2. Fix duplicates in the system you treat as the source of truth, usually the POS.
  3. Edit the other system to the same values, then run the check again on both lists together.
  4. Only then switch on sync. In StockEven, products without a match are listed with the reason, so nothing is overwritten by mistake.

Questions

Is my data sent anywhere?

No. The check runs in JavaScript in this page. Nothing is uploaded or stored.

How many SKUs can it handle?

Tens of thousands of lines. The limit is the browser, not a quota.

Does a product need a SKU to sync?

For SKU-based sync tools, including StockEven, yes. Products without a SKU are skipped and listed so they can be fixed.