Walmart Marketplace Integration: A Complete Guide for Developers

Walmart is one of the fastest-growing marketplaces in the United States, attracting more than 255 million weekly customers across its global retail and online ecosystem. Moreover, Walmart.com alone generates over 531 million monthly visits, making it one of the most visited eCommerce websites in the U.S. With an estimated 200,000 active Marketplace sellers in 2025, connecting your software to this ecosystem can significantly enhance your product’s value and reach.

Building a reliable Walmart marketplace integration allows SaaS providers to automate listings, sync inventory, process orders, handle shipments, and support high-volume Walmart sellers efficiently. In addition, for many vendors, becoming compatible with Walmart is a highly strategic move due to the platform’s rapid eCommerce growth.

In this guide, you’ll learn how Walmart integration works on a technical level, what challenges developers usually face, and how API2Cart simplifies integration across Walmart and 60+ other platforms. Furthermore, we’ll explore workflows related to ShipStation Walmart integration and demonstrate a real API response to improve clarity and implementation confidence.

Why Walmart Marketplace Integration Matters

A successful connection with Walmart Marketplace helps developers support merchants who want to grow their multichannel presence. As a result, SaaS providers can expand their functionality and address new customer demands. Some compelling reasons include:

• Access to over 120 million monthly Walmart.com shoppers.
• Opportunity to work with enterprise-level sellers operating at scale.
• Real-time sync of inventory, pricing, and order data.
• Automation of workflows traditionally requiring manual involvement.
• Instant expansion of supported sales channels for your SaaS product.

How Walmart Integration Works

The core of integration Walmart functionality lies in connecting your system to Walmart APIs, exchanging data between the marketplace and your platform, and ensuring stable synchronization. Consequently, your application can deliver accurate and timely information to sellers.

1. Authentication and Security

Walmart uses API key–based authentication combined with signature-based request verification. Therefore, each request requires proper hashing, timestamps, and headers.

2. Product and Catalog Operations

Through Walmart’s API, your system can:

• Create and update product listings
• Sync pricing and promotions
• Manage inventory levels
• Upload media and attributes

3. Order and Fulfillment Operations

Order workflows available via API integration Walmart include, for example:

• Retrieving new orders and updates
• Submitting shipment details
• Updating fulfillment status
• Cancelling or refunding orders

These operations are essential for building solutions like order management systems, shipping tools, inventory apps, and multichannel platforms. Furthermore, they ensure that merchants maintain full control over their sales channels.

Example Walmart API Response (Shipment Add)

To illustrate how Walmart API behaves in real integration scenarios, below is a response example from OrderShipmentAdd. This endpoint returns shipment confirmation details after sending tracking information.

{
  "return_code": 0,
  "return_message": "Order shipment successfully added",
  "result": {
    "shipment_id": "SH123456789",
    "order_id": "1234567890",
    "tracking_number": "1Z999AA10123456784",
    "carrier_code": "UPS",
    "status": "Created",
    "created_at": "2024-01-15T10:52:00Z"
  }
}

This structure helps developers understand the data returned after submitting shipment details. Additionally, it includes shipment identifiers, associated order information, carrier and tracking data, and the processing timestamp.

Challenges Developers Commonly Face

• Signature validation and timestamp formatting
• Strict product content requirements
• Lengthy feed processing for catalog uploads
• Rate limiting for high-volume accounts
• Maintaining separate integrations for each marketplace

Because of these complexities, many SaaS teams prefer not to build integrations manually from scratch. Therefore, they often rely on unified API solutions to speed up delivery.

How API2Cart Simplifies Walmart Integration

API2Cart provides a single unified API allowing developers to connect with Walmart and 60+ marketplaces and eCommerce platforms simultaneously. Consequently, this eliminates the need for maintaining separate integrations.

What you can do through API2Cart:

• Retrieve Walmart orders
• Sync inventory across channels
• Manage listings and pricing
• Add shipments and tracking numbers
• Access customer and order data in unified format

Additionally, API2Cart is especially useful for SaaS products that must support workflows similar to ShipStation Walmart integration, enabling cross-platform shipping automation.

Best Practices for Stable Walmart Integration

• Use queue-based architecture to handle feeds and order updates
• Log all Walmart API errors for debugging and data correction
• Implement retry logic for feed polling
• Sync stock frequently to avoid overselling
• Monitor rate limits and adjust request frequencies dynamically

Conclusion

Connecting your SaaS to Walmart Marketplace opens the door to enterprise-level merchants and significantly enhances your product’s capabilities. Moreover, automated workflows and reliable data exchange help reduce operational overhead and create a better experience for sellers.

Such integrations also enable your platform to support omnichannel retailers and unlock new commercial opportunities. As a result, by leveraging unified API solutions, you can accelerate development and stay focused on product innovation rather than maintaining multiple marketplace connectors.

If you want to test how API2Cart can simplify and speed up your Walmart integration, feel free to request 14-Day Free Trial and get expert guidance.