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The Best Way to Merge Walmart Marketplace and Mercari Data for Refund Reconciliation
If you're doing refund reconciliation by hand right now, here's the fastest path from "two exports" to "one usable sheet," and why the manual version keeps breaking.
Step by step
- Decide your target columns once. Most people settle on Date, Channel, Order ID, and Total — set that up in CSV Experts and you won't redo it.
- Import the Walmart Marketplace file first. The first time you see this file shape, you map each of its columns to your target list.
- Import the Mercari file the same way. Its columns get mapped once too — after that, every future file with this shape merges with no extra clicks.
- Check the merged totals. Dates and numbers are normalized automatically, so a European "24,00" and a US "24.00" both land as the same value.
- Export. CSV or Excel, ready for refund reconciliation.
What actually goes wrong if you do this by hand
Walmart Marketplace gives you an Order Date column separate from the ship-by date, while Mercari gives you a sold date in the seller's local time — line those up manually across a few hundred rows and it's easy to miscount a week. On top of that, Walmart Marketplace's export each order line can appear as its own row with a repeated order ID, similar to Shopify's line-item export, and Mercari's like other reseller apps, the export is minimal with no tax breakdown and mixes cancelled orders into the same file. Individually those are minor quirks; combined into one spreadsheet by hand, they're where most reconciliation errors for refund reconciliation actually come from.
Why it matters for refund reconciliation
Refunds are recorded differently enough between platforms that matching them back to original orders is one of the most error-prone manual tasks.
Just want the quick column-difference reference instead? See the short version.