Walmart Marketplace API Integration
Walmart Marketplace sellers connect through Walmart's API, not EDI. We build that connection inside your ERP: WFS and seller-fulfilled orders imported into one queue, seller-fulfilled orders confirmed with tracking, WFS orders shipped and invoiced automatically, returns turned into credit memos, and WFS inbound shipments created through the API. No middleware.
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Walmart Marketplace API vs Walmart supplier EDI
Walmart runs two different programs. Marketplace sellers, the third-party (3P) side, list and sell on Walmart.com and connect through Walmart's API. Suppliers who sell to Walmart directly, the first-party (1P) side, exchange X12 EDI documents.
The two have different onboarding and different rules. This page covers the Marketplace API. For the supplier side, see Walmart EDI integration.
What a Walmart API integration covers
- Order import for WFS and seller-fulfilled orders. Walmart Fulfillment Services (WFS) orders and seller-fulfilled Marketplace orders are both imported into the ERP, into the same order queue as your other channels.
- Automatic shipping and invoicing for WFS orders. Walmart ships WFS orders from its own stock, so the ERP marks them shipped automatically and generates the invoice from that shipment.
- Shipment confirmation for seller-fulfilled orders. When you ship a seller-fulfilled order, the shipment confirmation and tracking number are sent back to Walmart through the API.
- Returns as credit memos. Walmart returns are imported and converted into credit memos in the ERP, so accounting and stock both reflect the return.
- WFS inbound shipments. Inbound shipments to Walmart's fulfillment centers are created through Walmart's API from the ERP, the same pattern used for Amazon FBA inbound.
- A Walmart stock location in the ERP. Inventory is not pushed to Walmart. The ERP keeps a dedicated Walmart location that mirrors the stock held at Walmart. Confirmed inbound receipts and returns increase it. Every Walmart order decreases it.
How we build Walmart API integration inside your ERP
Orders
WFS and seller-fulfilled orders land in one queue with Amazon, Shopify and your other channels. Seller-fulfilled orders are confirmed back to Walmart with tracking.
Fulfillment and invoicing
WFS orders are marked shipped in the ERP automatically, and the invoice is created from that shipment.
Inventory
A Walmart location in the ERP rises when Walmart confirms an inbound receipt or a return is credited, and falls with every order. Walmart keeps its own count, and the integration does not overwrite it.
Inbound to WFS
Inbound shipments are created through the API, the same way as Amazon FBA inbound. When Walmart confirms receipt, the received quantity is added to the Walmart location.
Walmart Marketplace API in a live multi-channel ERP
- Walmart runs through Walmart's API, not EDI.
- WFS and seller-fulfilled Walmart orders are imported into the same ERP order queue as Amazon, HSN, QVC, Costco, Shopify and eBay.
- WFS orders are marked shipped automatically in the ERP, and the invoice is generated from that shipment.
- Seller-fulfilled orders send shipment confirmation and tracking back to Walmart through the API.
- Walmart returns are imported and converted into credit memos in the ERP.
- WFS inbound shipments are created through Walmart's API, the same pattern as Amazon FBA inbound.
- A dedicated Walmart location mirrors stock held at Walmart. Inbound receipts and returns increase it, and every order deducts from it. Inventory is not pushed to Walmart.
- Shipping labels come from live FedEx, UPS and USPS rate shopping, and inventory is tracked across multiple warehouses, including the Walmart location.
What typically breaks with Walmart API syncs
- Expired or revoked API credentials stop the scheduled sync Orders stop arriving, but nothing looks broken in the ERP. The sync log shows authentication failures on every run. The fix is new credentials from Seller Center, and an alert on repeated auth failures so the gap is caught in hours, not days.
- Rate limits during high order volume During a sale or the holiday peak, calls start getting throttled and some runs finish without pulling every order. The log shows throttling responses. The sync has to back off, retry, and resume from where it stopped rather than skip ahead.
- Shipment confirmation rejected by Walmart A seller-fulfilled order shows shipped in the ERP but not on Walmart. The rejected response usually points at the carrier name, the service method or the tracking number format. The fix is in the carrier mapping, and the order is resent once it is corrected.
- The ERP's Walmart location drifts from Walmart's count The ERP mirrors stock at Walmart; it does not control it. Drift usually starts with a partial inbound receipt, where Walmart receives fewer units than were shipped. Comparing the ERP location against Walmart's inventory report shows the gap, and an adjustment against the specific inbound shipment brings the two back in line.
Walmart API integration questions
Do Marketplace sellers need EDI for Walmart?
No. Walmart Marketplace sellers connect through Walmart's API. EDI is for suppliers who sell to Walmart directly, which is a separate program with its own onboarding.
Do we need a middleware tool?
No. The integration is code inside your ERP that calls Walmart's API directly. There is no connector tool or second system sitting between your ERP and Walmart.
Can WFS and seller-fulfilled orders run through the same system?
Yes. Both import into the same ERP order queue as your other channels. After import they follow different paths. WFS orders are marked shipped and invoiced automatically. Seller-fulfilled orders go through your own fulfillment, then shipment confirmation and tracking go back to Walmart.
Do you push inventory quantities to Walmart?
No. Walmart manages its own inventory count. The ERP mirrors it in a dedicated Walmart location, updated by confirmed inbound receipts, orders and returns.
What happens to inventory when a Walmart order is returned?
The return is imported and converted into a credit memo in the ERP. The credit memo adds the returned quantity back to the Walmart location.
How often are orders pulled?
The sync runs on a schedule set for each client, based on order volume and how quickly orders need to reach fulfillment.
Does this work with an ERP you did not build?
Often yes. What matters is whether your order, inventory and invoicing data is reachable, not who wrote the ERP. We confirm that during scoping, before any build work starts.
Who owns the integration code?
You do. It sits in your ERP codebase.
Related to Walmart API integration
Are Walmart orders still being keyed in by hand?
Tell us whether you sell through WFS, seller-fulfilled or both, and what your ERP runs today. We will tell you what a direct Walmart API integration would take off your team's plate.