Do your channels agree on what you have?

Where to get the two files

It reads three exports by name and works out the columns for you. Anything else that is a CSV or tab-separated file with a SKU column and a quantity column works too; you pick the two columns.

• Shopify: Products, then Inventory, then Export. It compares the Available column, added up across your locations.
• Amazon FBA: Reports, then Fulfillment, then the Manage FBA Inventory report. It compares afn-fulfillable-quantity, the units Amazon can ship now.
• Amazon merchant-fulfilled: the All Listings report from Inventory Reports. It compares the quantity column.
• Anything else: a Walmart or eBay download, your 3PL's stock file, or the spreadsheet you keep by hand.

How it compares

SKUs are matched ignoring upper and lower case and extra spaces. Nothing looser than that, because pairing two SKUs that are really different products would hide the very mismatch you came to find. If one file lists a SKU on several rows, one per location for example, those rows are added up. A blank quantity stays blank. It is never counted as zero.

Not every difference is a mistake. If you hold back a buffer on one channel, or one system has already taken out units for open orders and the other has not, the numbers should differ. The table shows where they do. You know which of those you meant.

What happens to your files

Nothing leaves your computer. The comparison runs in this page, and the download button builds the CSV in your browser too. This site records visits, with typing masked and no IP addresses kept, to find broken pages, and the whole tool is excluded from that recording, so your SKUs and counts are not in it. If you want to check, open your browser's network tab before you drop a file in.

Why I built it

A conversation I have often with operators starts with a sync tool that said everything was fine. The stock on one channel had drifted from the stock on another for weeks, and nobody knew until orders came in for things that were not on the shelf. By then the question is not whether the counts are wrong. It is how wrong, and where. That is a spreadsheet job usually done by hand, three exports at a time, and this does the lining-up part for two of them.

If the result is a handful of SKUs a few units apart, that is a buffer or a timing gap and you probably do not need new software. If it is hundreds of SKUs, the cost of that in oversells is something you can put a number on with the oversell cost calculator. And if you would rather read than talk, the newsletter is inventory and multichannel operations writing, sent when there is something worth sending.