Amazon ASIN Lookup & Buy Box Monitor

Feed it a list of ASINs, get back product detail, the Buy Box seller, stock, return policy and the full variation family — plus price and Buy Box changes since your last run.

Built for retail arbitrage and dynamic-pricing sellers.

No login, no API key. HTTP-only — no browser.

Read this before you buy: Amazon withholds the offer block

This is the single most important thing about scraping Amazon product pages anonymously, and it decides whether this actor fits your use case.

Amazon serves logged-out visitors two different versions of a product page, deterministically per ASIN:

	Full page	Reduced page
Title, brand, rating, reviews, BSR, images, variations	✅	✅
Price	✅	❌ not served
Buy Box seller / seller ID	✅	❌ not served
Ships from, return policy	✅	❌ not served

Measured over 10 successfully fetched ASINs: 6 full, 4 reduced. Price and seller always appear together — Amazon serves the whole offer block or none of it.

The reduced page is not a transient failure. The same ASIN was refetched 6 times across 4 TLS fingerprints and returned the reduced page every time. Warming a session first, reusing cookies, ?th=1&psc=1, /gp/offer-listing/, and the aod all-offers endpoints were all tested — none of them make the offer block appear. It is not something a retry, a proxy or a better fingerprint fixes.

So every row carries buyBoxDataAvailable. When it is false, the seller fields are null because Amazon did not serve them — not because Amazon is the seller. Never read a null seller as "sold by Amazon".

buyBoxDataAvailable = true   ->  price, seller, returns are real
buyBoxDataAvailable = false  ->  those fields are UNKNOWN, not empty

If your workflow needs seller data on 100% of ASINs, this actor will not deliver it and neither will any other logged-out scraper — that data is behind Amazon's SP-API.

What you get

{
  "asin": "B00XIKPUK4",
  "title": "NAKED Whey 2LB 100% Grass Fed Whey Protein Powder",
  "brand": "Naked Nutrition",
  "price": 62.99,
  "currency": "$",
  "inStock": true,
  "condition": "New",
  "rating": 4.3,
  "reviewCount": 10766,
  "bestSellersRank": 288,
  "bestSellersCategory": "Health & Household",
  "buyBoxDataAvailable": true,
  "buyBoxSellerId": "A2GB0T0Z517LEH",
  "buyBoxSellerName": "Naked Nutrition Inc",
  "buyBoxIsAmazon": false,
  "shipsFrom": "Amazon",
  "returnPolicy": "Non-returnable",
  "parentAsin": "B0CS4S2TWH",
  "variationCount": 19,
  "variationDimensions": ["Size", "Flavor Name"],
  "changeType": "PRICE_DECREASED",
  "previousPrice": 68.99,
  "priceDelta": -6.0,
  "priceDeltaPercent": -8.7
}

Field coverage over 10 fetched ASINs:

Field	Coverage
title, rating, reviewCount, parentAsin	10/10
bestSellersRank, imageUrl, childAsins	9/10
brand, featureBullets	8/10
price, currency, Buy Box seller	6/10
shipsFrom, returnPolicy	4/10

Monitoring changes

Set trackChanges: true and the actor stores a snapshot in a named key-value store, then labels every row on the next run:

NEW · UNCHANGED · PRICE_INCREASED · PRICE_DECREASED
BUYBOX_SELLER_CHANGED · BACK_IN_STOCK · OUT_OF_STOCK

Schedule it and you have a Buy Box watch on your ASIN portfolio.

A withheld offer block never fires a false alert. If Amazon served a seller last run and withheld it this run, that is UNCHANGED, not BUYBOX_SELLER_CHANGED — otherwise ~40% of your portfolio would alert on every single run. The same guard applies to stock.

Use different snapshotName values to track separate portfolios.

Input

{
  "asins": ["B00XIKPUK4", "B06XX65GS1", "https://www.amazon.com/dp/B01MQQ4RFA"],
  "marketplace": "com",
  "trackChanges": true,
  "expandVariations": false
}

Field	Description
asins	ASINs to look up. Product URLs work too — the ASIN is extracted
marketplace	com, co.uk, de, fr, it, es, ca, com.au, co.jp, in
includeVariations	Capture parent/child ASINs and dimensions (default on)
expandVariations	Also scrape each child as its own row, for per-variant prices
maxVariationsPerAsin	Cap children fetched per product (default 5)
trackChanges	Compare against the previous run
snapshotName	Named store for the snapshot — one per portfolio
delaySeconds	Pacing between products
proxyConfiguration	Residential strongly recommended

Things worth knowing

Prices are pinned to the marketplace currency. Amazon prices from the request's geo-IP — an Indonesian exit returned IDR 336,939.57 for a $19.99 item. The actor sends the cookie that forces the marketplace's currency, so figures stay comparable wherever the run exits from. currency is on every row regardless, so never assume USD.

A null price is a null price. The reduced page still contains dozens of a-offscreen price spans belonging to related products and other variants. Reading the first one gave one $25 protein powder a price of $2489.00. The actor only accepts a price from Amazon's canonical price containers, so a product whose price was not served reports null rather than a plausible wrong number. For a repricing tool that distinction is the whole ballgame.

inStock is tri-state. null means Amazon served no stock signal — not "out of stock". A cart button on a reduced page is not counted as proof of stock, because that button is rendered even when no offer exists.

Blocked ASINs are reported, never silently dropped. A bot wall emits a CAPTCHA_ESCALATION row so a short run is never mistaken for a short catalogue. CAPTCHAs are never solved. Expect some blocking without a residential proxy — 2 of 12 ASINs were blocked from a home IP in testing.

Known limits

• Buy Box / seller / returns on ~60% of ASINs, for the reason above.
• Only the Buy Box offer, not the full offer list. The all-offers panel (aod) returns 404 to logged-out clients, so competing-seller counts and used/refurbished prices are not obtainable — condition reflects the New offer shown.
• No sales estimates or bid data — no public surface exposes them.
• Variation children are only expanded one level, from the ASINs you supply.

See CRAWLING_METHOD.md for the fingerprint matrix, the full-vs-reduced page investigation, and every endpoint that was ruled out.