Multi Channel Selling

Step 2: Set up your primary store as the inventory master

Before connecting any channels, ensure your primary store has:

• Accurate stock levels for all SKUs
• Product dimensions and weights entered (required for marketplace listings)
• HS codes if selling internationally
• UPC/GTIN barcodes on all products (required for Amazon and Walmart listings)

Shopify

1. Go to Settings → Sales channels — Shopify lists all available channels
2. Add Facebook & Instagram (free, by Meta) to sync products to your Facebook Shop and Instagram Shopping
3. Add Google & YouTube (free, by Google) to sync products to Google Shopping
4. For Amazon: install Codisto or Sellbrite from the Shopify App Store — these handle the Amazon SP-API integration

WooCommerce

1. Your WooCommerce store is the inventory master
2. Install WP-Lister Pro for Amazon and/or WP-Lister Pro for eBay from wpla.net
3. WP-Lister reads your WooCommerce products and creates Amazon/eBay listings from them
4. Orders from Amazon/eBay are imported back to WooCommerce automatically

BigCommerce

1. Go to Channel Manager in BigCommerce admin (available on all plans)
2. Connect Google Shopping, Facebook, Instagram via the native channel connectors
3. For Amazon and eBay: install Codisto from the BigCommerce App Marketplace — it's the recommended Amazon/eBay integration for BigCommerce

Step 3: Connect marketplace channels

Amazon

Amazon requires a Professional Seller account ($39.99/month) and approved product categories. You'll also need GTINs (UPCs or ASINs) for every listing.

Via Shopify + Sellbrite:

1. Install Sellbrite from the Shopify App Store
2. Connect your Amazon Seller Central account in Sellbrite → Channels → Add Channel → Amazon
3. Sellbrite imports your existing Amazon ASINs if you already have listings, or you can create new listings from your Shopify products
4. Enable inventory sync: Sellbrite pushes your Shopify inventory quantity to Amazon in real time (within minutes of a sale on either channel)
5. Amazon orders import into Sellbrite and sync to Shopify as new orders automatically

Via WooCommerce + WP-Lister:

1. Connect your Amazon Seller Central account in WP-Lister Pro → Amazon → Settings
2. Map your WooCommerce products to ASINs (match by UPC/GTIN or search Amazon's catalog)
3. WP-Lister syncs inventory from WooCommerce to Amazon and imports Amazon orders to WooCommerce

eBay

Via Shopify + Sellbrite:

1. In Sellbrite, go to Channels → Add Channel → eBay
2. Connect your eBay Seller account via OAuth
3. Map Shopify products to eBay listing templates; Sellbrite handles category requirements and eBay-specific fields
4. Inventory syncs both ways in near real time

Via WooCommerce + WP-Lister:

1. Same setup as Amazon — connect your eBay account in WP-Lister Pro → eBay → Settings
2. Create listing templates in WP-Lister to map WooCommerce product data to eBay category requirements

Walmart Marketplace

Via Shopify + Sellbrite:

1. Walmart Marketplace requires an application and approval (apply at marketplace.walmart.com)
2. Once approved: connect Walmart in Sellbrite → Channels → Add Channel → Walmart
3. Sellbrite handles Walmart's specific listing requirements (requires GTIN, specific image dimensions)

Via BigCommerce + Codisto:

1. Apply for Walmart Marketplace approval separately
2. Once approved: connect Walmart in Codisto → Channels → Walmart
3. Codisto syncs products and inventory automatically

Step 4: Configure inventory allocation per channel

When one channel sells out, you want to prevent other channels from showing stock you don't have. Most channel management tools handle this — configure buffer quantities per channel.

In Sellbrite:

1. Go to Sellbrite → Channels → [Channel] → Inventory Settings
2. Set "Channel Buffer": e.g., keep 5 units in reserve so Shopify always has stock even if Amazon buys the rest
3. Enable "Stop selling when inventory = 0" to prevent oversells

In Linnworks:

1. Linnworks → Settings → Stock Management → Configure per-channel stock allocation
2. Set safety stock levels per channel to prevent one channel from consuming all inventory

In Codisto (BigCommerce):

1. Codisto → Inventory → Configure "Available stock formula": e.g., BigCommerce stock - 3 for Amazon (holds 3 units back for other channels)

Step 5: Handle orders from all channels

Every channel order should flow into your central system and trigger fulfillment from the same process.

Shopify with Sellbrite:

• Amazon and eBay orders import to Sellbrite and sync to Shopify as regular orders
• Fulfill in Shopify normally — ShipStation or Shopify Shipping handles label creation
• Sellbrite pushes tracking numbers back to Amazon/eBay automatically (required within 2 business days for Amazon)

WooCommerce with WP-Lister:

• Amazon and eBay orders import to WooCommerce as regular orders
• Fulfill in WooCommerce (or ShipStation); tracking numbers sync back to the marketplace automatically

Linnworks (any platform):

• All orders from all channels appear in Linnworks → Orders in one view
• Create pick lists and shipping labels in Linnworks
• Linnworks pushes fulfillment confirmation and tracking to each channel automatically

Custom / Headless — cross-channel order ingestion

// Normalize an order from any marketplace into a common format
interface NormalizedMarketplaceOrder {
  channelName: string;       // 'amazon', 'ebay', 'walmart', 'shopify'
  channelOrderId: string;    // the marketplace's order ID
  lines: {
    channelSku: string;
    masterSku: string;       // your internal SKU
    quantity: number;
    unitPriceCents: number;
  }[];
  shippingAddress: Address;
  customerEmail: string;
}

async function ingestMarketplaceOrder(order: NormalizedMarketplaceOrder): Promise<void> {
  // Idempotency: skip if already imported
  const existing = await db.orders.findByChannelOrderId(order.channelName, order.channelOrderId);
  if (existing) return;

  await db.transaction(async tx => {
    // Create the order in your system
    const createdOrder = await tx.orders.insert({
      channel: order.channelName,
      channel_order_id: order.channelOrderId,
      status: 'awaiting_fulfillment',
      shipping_address: order.shippingAddress,
      customer_email: order.customerEmail,
    });

    // Reserve inventory for each line
    for (const line of order.lines) {
      await tx.orderLines.insert({
        order_id: createdOrder.id,
        sku: line.masterSku,
        quantity: line.quantity,
        unit_price_cents: line.unitPriceCents,
      });
      // Decrement inventory immediately
      await tx.raw(
        'UPDATE inventory SET reserved = reserved + ? WHERE sku = ? AND (quantity_on_hand - reserved) >= ?',
        [line.quantity, line.masterSku, line.quantity]
      );
    }
  });
}

Step 6: Monitor cross-channel performance

Track per-channel metrics monthly to understand your channel economics:

Best Practices

• Never maintain separate stock counts per channel — one pool, updated immediately after every sale on any channel; stale inventory leads to oversells
• Use channel-specific SKU mappings — Amazon uses ASINs, eBay uses item IDs, your store uses your internal SKU; maintain a mapping table rather than exposing your internal SKUs to marketplaces
• Set safety stock buffers per channel — allocate a reserve so one channel can't sell out your entire inventory before the sync propagates to other channels
• Test with a single product before scaling — connect one product to Amazon, verify the listing, place a test order, and confirm inventory syncs before connecting your entire catalog
• Log all channel sync failures with retry — marketplace API calls fail intermittently; use your channel management tool's retry logic and review the failure log weekly

Common Pitfalls

Related Skills

• @order-management-system
• @vendor-management
• @b2b-commerce
• @dropshipping-integration
• @marketplace-building