Free tool
Duplicate SKU checker for Shopify
Drop in your Shopify product export to find every SKU on more than one variant, every variant with no SKU, and SKUs typed two ways. Add a second store's export to see which SKUs match between them. It all runs in your browser: the file never leaves your computer.
Store 1
How to export your products from Shopify
- In your Shopify admin, open Products.
- Choose Export, at the top of the page.
- Pick All products and either CSV format, then Export products.
- Shopify downloads the file, or emails it to you when the catalogue is large.
Do the same in your other store to compare the two. Each store's file goes in its own box above, and none of them are uploaded.
What it checks
- SKUs on more than one variant
- The same SKU on two variants, in one product or across several. An app that matches stores by SKU cannot tell which one another store's SKU means. Sometimes it is a real error, two different items wearing one code; sometimes it is one item sold as two products, which wants one shared count instead.
- Variants with no SKU
- Nothing that matches by SKU can sync them. Gift cards and variants that track no stock are not counted.
- Look-alike SKUs
- SKUs that differ only in spaces or punctuation, such as SHIRT-M and SHIRT_M: separate SKUs that are often one item typed two ways.
- SKUs with a space at the start or end
- Invisible in the admin, and enough to stop an app that compares SKUs exactly from matching them.
- Across two or more stores
- Which SKUs match one-to-one, which each store is missing (with a look-alike it does have, when there is one), and which are written differently from one store to the other.
Why these matter before you connect stores, and how each one goes wrong in a sync, is in Duplicate SKUs and why sync goes wrong.
Common questions
Is my product file uploaded anywhere?
No. The checker reads the file inside your browser and sends nothing from it anywhere; once this page has loaded you can go offline and it still works. The page counts that the checker ran and how many of each problem it found, never the SKUs or product names themselves, and the results are left out of this site's session recordings.
Which Shopify export does it need?
The product export: in your Shopify admin, open Products, choose Export, and export all products as a CSV file. Either CSV format works. The inventory export (Products, then Inventory, then Export) has one row per location, so it cannot be used to count duplicates, and the checker says so if you give it one.
Does Shopify stop two products having the same SKU?
No. Shopify accepts the same SKU on any number of variants and products and never warns about it, so duplicates build up quietly until an app uses the SKU to tell items apart.
What counts as the same SKU?
Spaces at the start or end are ignored and letters are compared regardless of case, so abc-1 and ABC-1 are one SKU. That is the rule StockUnison matches by. SKUs that differ only in punctuation, such as SHIRT-M and SHIRT_M, are different SKUs; the checker lists them as look-alikes, because they are often one item typed two ways.
Is a duplicate SKU always a mistake?
No. Two different items wearing one SKU is a mistake, and no app that matches by SKU can sync it correctly. One item sold as two products, such as a mug sold on its own and in a gift set, is not a mistake: it is one shelf, and the fix is one shared count for both products rather than a new SKU.
Why are draft and archived products left out?
StockUnison keeps only products that are for sale in sync, active or unlisted, because an archived copy of a live product often still carries its SKU. Tick Include draft and archived products to check those too.
How big a catalogue can it check?
The file is read in pieces, so an export of hundreds of megabytes works, and a store with 100,000 variants takes seconds on a laptop. A large store's export that arrives as several files can be chosen all at once for the same store.
Does it change anything in my store?
No. It only reads the file you give it, and it has no access to your store at all.