MCS order flow — Shopify to Walmart

When a customer places an order on your Shopify store (or any connected sales channel):

• Shopify fires a webhook to the app
• The app checks which sales channel the order came from and matches it to a configured MCS Channel ID
• It verifies that all products in the order have SKU mappings to Walmart
• When Shopify signals that fulfillment should begin (either automatically when the order is paid, or when you or a Shopify Flow workflow submits a fulfillment request), the app sends the order to Walmart MCS
• Walmart picks, packs, and ships the order from your WFS inventory
• The app polls Walmart for status updates and writes tracking information back to the Shopify order

WFS order flow — Walmart to Shopify

When a customer places an order on Walmart.com and Walmart ships it from your WFS inventory:

• The app polls the Walmart WFS Orders API on a regular schedule
• New Walmart.com orders are created as Shopify orders automatically (if you have this setting enabled)
• Tracking information from Walmart is synced to the corresponding Shopify order

Inventory sync

The app periodically fetches your WFS inventory levels from Walmart and updates the Walmart Fulfillment Services location in Shopify. This inventory level determines whether Shopify routes fulfillment orders to the app in the first place — if a product shows zero stock at your WFS location, Shopify will not route its fulfillment orders here.

Inventory is tracked per SKU with three quantities:

• Available to Sell — units Walmart can ship right now
• Inbound — units in transit to Walmart's warehouses
• Reserved — units allocated to open orders

Returns

When a WFS or MCS return is initiated, the app syncs the return record from Walmart back to Shopify. Return status moves through: Initiated → In Transit → Received → Completed.

Webhook events handled

The app listens for the following Shopify events:

• Event: Purpose
• Order created: Start MCS fulfillment process
• Order paid: Confirm payment before sending to Walmart
• Order cancelled: Cancel the corresponding Walmart MCS order
• Fulfillment request submitted: Trigger MCS order creation
• Fulfillment order routed: Fallback signal to start fulfillment
• Fulfillment order on hold: Pause processing (e.g. TikTok channel hold)
• Fulfillment order hold released: Resume processing
• Cancellation request submitted: Cancel MCS order at Walmart
• App uninstalled: Deactivate the store record