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Merge Walmart Marketplace and Mercari Sales Data for Year-End Sales Summary

A year-end summary across channels means twelve months of exports from each platform, all needing the same cleanup before they can be totalled together.

Why Walmart Marketplace and Mercari exports don't line up

Walmart Marketplace: an Order Date column separate from the ship-by date; item price and a separate Walmart referral fee; a numeric Purchase Order ID. Also, each order line can appear as its own row with a repeated order ID, similar to Shopify's line-item export.
Mercari: a sold date in the seller's local time; item price and Mercari's selling fee shown separately, with shipping often bundled into the price; an order ID tied to a single sold item. Also, like other reseller apps, the export is minimal with no tax breakdown and mixes cancelled orders into the same file.

For year-end sales summary, that mismatch is exactly what causes hours of manual cleanup every period.

How to merge them in under a minute

Open CSV Experts and set your target columns once (Date, Channel, Order ID, Total).
Drop in your Walmart Marketplace export and map its columns once.
Drop in your Mercari export and map it the same way — both merge into one sheet, normalized.
Export as CSV or Excel. Same-layout files merge automatically next time.

Merge your files now →

FAQ

Does this upload my sales data anywhere?

No. Everything runs in your browser using JavaScript — your files are never sent to a server.

Does it work for more than two channels?

Yes. Add as many source files as you want; each distinct file layout is mapped once and remembered.

Prefer a longer walkthrough of this pair? See the step-by-step version.

More Walmart Marketplace + Mercari guides

Other channel pairs for Year-End Sales Summary

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