Tutorial

How to Build a Cross-Listing Data Layer

An r/reselling post asked for cross-listing tool options. Build a data layer over Amazon + Walmart + Google Shopping with Scavio.

Cross-listing tools sync inventory across marketplaces. The data layer behind them is where complexity lives. This tutorial builds a Scavio-backed multi-marketplace data layer.

Prerequisites

  • Python 3.10+
  • Scavio API key

Walkthrough

Step 1: Define your marketplaces

Amazon + Walmart + Google Shopping covered by Scavio.

Python
MARKETPLACES = ['amazon', 'walmart', 'google_shopping']

Step 2: Per-SKU price check

One call per marketplace.

Python
import os, requests
H = {'x-api-key': os.environ['SCAVIO_API_KEY']}

def price(sku, mp):
    if mp == 'amazon':
        return requests.post('https://api.scavio.dev/api/v1/amazon/search', headers=H, json={'query': sku}).json()
    if mp == 'walmart':
        return requests.post('https://api.scavio.dev/api/v1/walmart/search', headers=H, json={'query': sku}).json()
    return requests.post('https://api.scavio.dev/api/v1/search', headers=H, json={'query': sku, 'search_type': 'shopping'}).json()

Step 3: Compute per-SKU comparison

Lowest price across marketplaces.

Python
def compare(sku):
    rows = []
    for mp in MARKETPLACES:
        data = price(sku, mp)
        items = data.get('products') or data.get('shopping_results') or []
        for item in items[:3]:
            rows.append({'marketplace': mp, 'title': item.get('title'), 'price': item.get('price'), 'url': item.get('url')})
    return rows

Step 4: Reddit demand signal per SKU

Optional: r/Flipping discussion.

Python
def demand(sku):
    return requests.post('https://api.scavio.dev/api/v1/reddit/search', headers=H, json={'query': sku}).json()

Step 5: Wrap in a daily cron

Update prices and demand signal each morning.

Text
# Per 1,000 SKUs daily across 3 marketplaces:
# 3,000 Scavio queries = ~13 credits = $0.06/day.

Python Example

Python
# Total cost for a cross-listing tool tracking 1,000 SKUs daily: ~$2/mo of Scavio.

JavaScript Example

JavaScript
// Same architecture in TS.

Expected Output

JSON
Daily price + demand snapshot per SKU across 3 marketplaces. Output table feeds the cross-listing UI or the seller's pricing logic.

Related Tutorials

Frequently Asked Questions

Most developers complete this tutorial in 15 to 30 minutes. You will need a Scavio API key (free tier works) and a working Python or JavaScript environment.

Python 3.10+. Scavio API key. A Scavio API key gives you 500 free credits per month.

Yes. The free tier includes 500 credits per month, which is more than enough to complete this tutorial and prototype a working solution.

Scavio has a native LangChain package (langchain-scavio), an MCP server, and a plain REST API that works with any HTTP client. This tutorial uses the raw REST API, but you can adapt to your framework of choice.

Start Building

An r/reselling post asked for cross-listing tool options. Build a data layer over Amazon + Walmart + Google Shopping with Scavio.