multi-channel-selling

What this skill does

# Multi-Channel Selling

## Overview

Multi-channel selling lets you list products on your own website, Amazon, eBay, Walmart, and wholesale portals simultaneously — with inventory synchronized in real time so you never oversell. The critical rule: one inventory pool, updated immediately when any channel sells or restocks. Purpose-built channel management tools (Linnworks, Sellbrite, Skubana/Extensiv) make this manageable without custom integration work.

## When to Use This Skill

- When expanding beyond your own website to sell on Amazon, eBay, or Walmart Marketplace
- When running both a retail DTC site and a wholesale B2B portal from the same inventory pool
- When selling the same products under different brand names or content across channels
- When overselling on one channel because inventory is not shared in real time
- When building a channel management platform that lets brands manage all their sales channels in one place

## Core Instructions

### Step 1: Determine your platform and choose the right channel management tool

| Platform | Recommended Tool | Why |
|----------|-----------------|-----|
| **Shopify** | Shopify's native Sales Channels + Sellbrite or Linnworks for external marketplaces | Shopify has built-in Facebook, Instagram, Google, and TikTok channels; Sellbrite adds Amazon/eBay/Walmart with inventory sync |
| **WooCommerce** | WP-Lister Pro (Amazon + eBay) or Linnworks | WP-Lister Pro lists products from WooCommerce directly to Amazon/eBay and syncs orders back |
| **BigCommerce** | BigCommerce Channels + Codisto (for Amazon/eBay) | BigCommerce has a native Channel Manager; Codisto extends it to Amazon, eBay, and Walmart with real-time sync |
| **Any Platform** | Linnworks or Skubana (Extensiv) as a central OMS | These tools sit above all channels and act as the single source of inventory truth for high-volume multi-channel operations |

### 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

```typescript
// 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 => {
    // C