Track Competitors' Shopify Prices and Stock Daily From Their Public Product Feed
A vendor's agent tool reads public Shopify product feeds every day and reports new and removed products plus price and stock changes. In its own one-day test it logged 10 variant stock changes at allbirds.com and 266 at gymshark.com (10,027 products read).
Who this is about: Shopify and direct-to-consumer sellers (vendor demo)
What it takes
- Cost
- FreeFree within rate and daily limits, with no sign-up or API key.Price checked Oct 15, 2026 on tools.openkrill.app. Prices change; check before you buy.
- Setup time
- Under an hourOur estimate from the source, for one business.
- Skill needed
- Some tech skillsComfortable installing an app, pasting an API key or running a command.
Explain it simply
Most Shopify stores publish a public list of their products, with prices and whether each size is in stock, at a web address ending in /products.json. A tracker reads that list once a day, saves a copy, and compares it with yesterday's to spot price cuts, sell-outs and new products. You can ask for that report through an AI assistant like Claude, so you get a quick morning summary of what rival stores changed.
What was done
OpenKrill tracked three stores daily: allbirds.com, gymshark.com and kyliecosmetics.com. The steps it describes:
Check if a site is a Shopify store: add /cart.json to the address. A store on a Shopify-hosted theme answers with a JSON cart, even an empty one. A 404 means "not a Shopify-hosted theme," not "not Shopify": gymshark.com returned 404 but its product feed still worked.
Read the catalog: /products.json lists each product's title, type, vendor, variants, price and availability per variant, up to 250 products per page with ?limit=250.
Keep daily snapshots: the feed has no stock counts, sales or past prices, so the tracker saves a snapshot every day and compares it with the previous one.
Read politely: it checks robots.txt first, names itself in every request, backs off when a store answers 429 (too many requests) and reads public product data only, with no cart, checkout or customer data.
How it went
From 2026-10-07 to 2026-10-08, allbirds.com had 692 products, 0 price changes and 10 stock changes, and gymshark.com had 6 new products, 0 price changes and 266 stock changes across 10,027 products read. Because gymshark's read stopped at the page limit, removed products weren't counted there, since a missing product might just be on a page it didn't fetch.
- This is the tool maker's own post about its own product, using big brands as test stores, and one day of data says nothing yet about how useful the alerts are for pricing decisions.
Prompt
1. Is it Shopify-hosted? https://[store]/cart.json -> JSON cart = yes
2. Catalog page 1: https://[store]/products.json?limit=250&page=1 (repeat page=2, 3... until empty)
3. Save each day's file and compare by variant ID:
new / removed products, price changed, available true<->false.
Ask in Claude with the tracker installed:
"Track [store].com daily and each morning tell me new and removed
products and any price or stock changes since yesterday."
Respect robots.txt and slow down if the store returns 429.The manual checks the post describes, in our words.
Business fit
Who this helps, and how:
Shopify and DTC sellers: get a morning digest of rivals' price cuts and sell-outs to time promotions and restocks.
Shopify & ecommerceMarketplace and dropshipping sellers: spot new products a competitor has added.
Shopify & ecommerceAgencies: add a simple competitor watch to client reports.
Agencies
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Similar tools
Other tools for this job, and how they differ. Chosen by our editors, never paid for.
- Prisync
Dedicated competitor price tracking for ecommerce catalogs.
- Price2Spy
Monitors rival prices and stock with alerts and reports.
- Competera
Pricing intelligence aimed at larger retail catalogs rather than a DIY feed scrape.
“Vendor or secondhand” (grade C) means: A tool maker's case study, a promotional demo, or someone else's write-up. How we grade. Spotted a mistake? Suggest a correction.