Vigia Price & Stock Delta

Monitor product prices and stock — pay only for what changes.

Point Vigia at public product pages, or give it a Shopify store URL to track its entire catalog, and get only meaningful changes: price up/down (with percent), back-in-stock and out-of-stock. It reads the structured product data (schema.org JSON-LD) shops publish publicly, and Shopify's public /products.json catalog feed.

Why choose Vigia

• Only changes, only charged for changes, at $0.007 — new products, price up/down, back-in-stock and out-of-stock. Removed and out-of-stock are delivered free. Most trackers bill you every run or every product checked, even when nothing moved — so the real amount you pay is usually higher than their sticker price.
• Whole-catalog Shopify coverage — give it a store URL and Vigia reads every product and variant from the store's public catalog feed, no anti-bot fragility.
• Amazon Best Sellers Rank tracking — give it ASINs and get price, stock, and BSR moves (bsr_improved/bsr_declined) — fetched via a chained, licensed Amazon actor, never scraped directly.
• "Lowest price ever" intelligence — in monitor mode Vigia remembers each product's price history and flags at_lowest_ever, pct_from_lowest and pct_from_average. Know a drop is a real all-time low, not noise.
• Move magnitude — every price change is tagged minor / moderate / major so you can filter the signal from the noise.
• Aggregate price signal — each run returns a price_signal: how many up/down, average drop %, biggest mover, total value shift. The story, not just rows.
• Percent price moves — every price change includes previous_price, price_change and price_change_pct.
• Delta monitoring — turn on monitor mode; later runs return only what changed since the last run.
• Fair pricing — hard maxTotalChargeUsd cap; never billed without a result.
• Clean output — structured JSON/CSV for your CRM, n8n or Make.

Input

• productUrls — public product page URLs, e.g. ["https://shop.example/products/widget"]
• shopifyStores — Shopify store domains, e.g. ["https://shop.example"], to track the whole catalog
• amazonAsins — Amazon ASINs to track, e.g. ["B01ABCDEF2"]
• monitorEnabled — first run stores a free baseline; later runs deliver only changes.
• monitorId — optional name to keep separate targets independent.
• maxTotalChargeUsd — hard spend cap for the run.

You can also pass your own currentProducts / previousProducts arrays if you bring your own data.

Output

One row per change: change_type (new / price_up / price_down / back_in_stock / out_of_stock / removed), name, price, previous_price, price_change_pct, magnitude, at_lowest_ever, pct_from_lowest, pct_from_average, in_stock, currency, source_url. Plus a RUN_SUMMARY.json with the aggregate price_signal.

Notes

• Reads only publicly published structured data. Respects a 1 MB page limit and blocks redirects.
• Price/stock changes are charged after delivery; removed and out-of-stock are free.