Amazon Inventory Checker: How Many Units Are Left, by ASIN

Give it a list of products. Get back how many units of each one can actually be ordered right now.

Not "in stock" or "out of stock", which you already knew. A number: three left, twelve left, or at least thirty. Run it daily and the difference between Tuesday's number and Friday's is how fast that listing is selling.

Every field it returns

Price and offer

Field	What it holds
price	Current price from Amazon's own buy box data
currency	Three-letter code, from the page itself
hasUsedOffer	Whether a used copy is offered
otherSellersCount	How many other sellers offer it

Stock and delivery

Field	What it holds
inStock	True, false, or null when Amazon does not say
availability	Amazon's own availability sentence
stockLeft	Only three left in stock, when shown
deliveryInfo	The delivery date Amazon promises
isPrime	Prime delivery on this offer

Identity and catalogue

Field	What it holds
asin	The product id
title	Full product title, shortened only past 1000 characters
brand	Brand name
marketplace	Which shop this row came from
url	The page this was read from
scrapedAt	Timestamp of the read

Stock level

Field	What it holds
stockAnswer	The verdict: an exact count, a seller order cap, or no answer (this is what you are charged for)
sellerStockLevel	How many units the buy box seller has left, when Amazon reveals it
stockSource	Where that number came from, so you can audit it

Read this before your first run

The number stops at thirty. Amazon's quantity menu offers at most thirty choices, so anything above that comes back as at-least:30 rather than a figure. This Actor will not invent what Amazon did not show.

That sounds like a big limitation and in practice it is the opposite of one. The useful signal is at the low end. A competitor sitting on four hundred units tells you nothing you can act on; a competitor down to six units next Thursday tells you exactly when their listing goes dark and yours is the only one left.

What the number really counts. It is the most you can put in a basket right now, which is the smaller of two things: how many the seller has, and how many they allow per order. Those two cannot be separated from outside, and pretending otherwise would produce a confidently wrong figure. So the field is called units, not stock, and this paragraph is on the page rather than buried.

It applies to the buy box seller. Other sellers on the same listing keep their own stock, and that is not visible here. otherSellersCount tells you how many of them there are.

Honest note about the famous trick. The method usually described for this, putting 999 in a basket and reading the error, is not what this Actor does. It was tried first: four rounds against the live site, three different routes, one of them a full replay of Amazon's own buy box form with its security token and a live session. Four of ten products had no such form at all and the other six answered with an error and an empty basket. What is in here reads the quantity menu on the page instead, which is the same underlying limit Amazon applies, and it needs no basket at all.

The four answers

Every row carries one of these in stockAnswer, or nothing.

Answer	What it means
units:7	Seven can be ordered right now.
at-least:30	The quantity menu was full. More than thirty, exact figure unknown.
out-of-stock	Amazon says it cannot be bought.
empty	Amazon revealed nothing usable. Delivered anyway, never charged for.

stockSource says where the number came from, so you can audit it: quantity-menu for Amazon's own order limit, scarcity-warning for the "Only N left in stock" line, availability for a plain no.

When both sources speak, the lower number wins. The menu limits what you can order and the warning describes what is on the shelf; taking the higher of the two would report stock that is not for sale.

What to put in

Products, three ways, same as everywhere in this family:

• an ASIN on its own, B09B8V1LZ3
• a product link, https://www.amazon.com/dp/B09B8V1LZ3
• pasted text with an ASIN in it, ASIN: B09B8V1LZ3

Search terms and category links work too, through search, if you would rather check the stock of whatever currently ranks for a keyword.

Settings worth knowing about

Setting	What it does
productUrls	The products to check. ASINs, links, or pasted text.
search	Search terms or category links, if you would rather check whatever ranks.
marketplace	Which Amazon. Nineteen available.
maxItems	Hard ceiling on products for this run.
maxItemsPerList	How many products to take from each search term or category.
maxListPages	How deep to page through a search or category.
proxyConfiguration	Which proxy to use. Datacenter by default.
proxyCountry	Which country to exit from. Empty means follow the marketplace.
residentialFallback	Switch the later attempts to residential addresses. Off by default; it costs more and, measured on this engine, it did not deliver more.
maxAttempts	How many times to retry a product Amazon refuses.
lanes	How many products to work on at once.
minDelayMs maxDelayMs retryPauseMs	The pacing. The defaults are deliberately unhurried.

How it works, in plain terms

It opens the product page, the same page a shopper sees, and reads two things Amazon prints there: the quantity menu next to the buy button, and the scarcity line that says "Only N left in stock" when a listing is running down.

The quantity menu is the interesting one. Amazon will not offer you a quantity you cannot have, so the number of choices in that menu is the order limit itself. A seller with five units gets a menu of five.

No basket is opened, no form is submitted, nothing is added anywhere. It is a read of a public page, which is why it works on the same pacing and the same retry logic as everything else in this family.

If Amazon refuses the page, it is retried from a different exit address up to maxAttempts times, and once more in a second pass at the end of the run. Only after all of that does a product come back without an answer, and free.

What you can build with it

Sales velocity without guessing. Snapshot a competitor daily. Five hundred on Monday is not visible, but twenty-two on Monday and fourteen on Friday is eight units in four days, and that is a real number rather than a model.

Stockout timing. When a competitor's number starts falling and yours does not, you know roughly when they run dry. That is the day to raise your price or push your advertising.

Supplier reliability. Watch your own listings across marketplaces. A number that drops toward zero while your own system says otherwise is a fulfilment problem you would otherwise find from a lost buy box.

Pre-purchase checks for arbitrage. Before you buy a hundred units to resell, check how thin the listing already is. A listing where the buy box seller has three left behaves very differently from one where they have thirty.

Scarcity as a research filter. Combined with the bestsellers scraper, a category full of listings sitting at units:2 is a category with supply problems, and supply problems are where margin lives.

Working it into your stack

Set a schedule and run it at the same hour daily, so consecutive numbers are comparable. Pull the dataset from the API:

https://api.apify.com/v2/datasets/<datasetId>/items?clean=true&format=csv

sellerStockLevel is a plain number when there is one, so a spreadsheet can subtract yesterday from today without any parsing. stockAnswer is the text version for the rows where there is no number.

Marketplaces

Nineteen, from amazon.com to amazon.co.jp. The quantity menu is read from the page structure rather than from any English wording, so a German or Japanese page is read the same way.

One caveat carries over from the rest of this family: on several marketplaces Amazon does not show a buy box to visitors it cannot place, and the quantity menu lives inside the buy box. Where there is no buy box there is no answer, and those rows arrive empty and free. Running twenty products on your own marketplace first costs almost nothing and tells you immediately whether this works for you.

Pricing

Four dollars per thousand products with an answer, plus three cents to start a run. That is four tenths of a cent per answer.

Checking a hundred products costs forty-three cents. Watching fifty daily costs twenty-three cents a day. You are not charged for a product where Amazon revealed nothing, or for one that never arrived. Platform usage is included, so there is no separate compute bill and no proxy bill.

The rest of this family

This Actor is one of thirteen on the same engine.

• Amazon Stock Checker when the question is simply buyable or not, with delivery promises, rather than how many.
• Amazon Listing Monitor to be told when something changes rather than reading the numbers yourself.
• Amazon Offer Checker for how many sellers are on the listing and on what terms.
• Amazon Price Tracker for the price on the same list of ASINs.
• Amazon Bestsellers Scraper to build the watch list in the first place.

They share the retry engine, the pricing model and the rule about never guessing, so what you learn on one carries to the others.

Questions people ask

Why do so many rows say at-least:30. Because most listings are not running low, which is itself the answer. The interesting rows are the ones that are not thirty.

Is the number the seller's real inventory. It is the most you can order right now. For a seller with no order cap those are the same thing; for one with a cap it is the cap. There is no way to tell from outside, and this page says so rather than picking the flattering interpretation.

Why is the number sometimes empty on amazon.de. Because Amazon sent a page without a buy box, which it does on several marketplaces when it cannot place the visitor. The quantity menu lives inside the buy box. Those rows cost you nothing.

Can I get more than thirty. Not from the page, and not from this Actor. The menu is where Amazon stops.

Does it add anything to a basket. No. Nothing is added, submitted or ordered. It reads a public page.

What it does not collect

No review text, no reviewer names, no customer questions, no seller names. Review text and reviewer names are personal data, and scraping personal data is almost always a problem under European privacy law regardless of intent. Star ratings and review counts are aggregate numbers and those are available in the sister Actors that report them.

You can see how many sellers are on a listing. You cannot see who they are.

Legal note

This Actor reads pages that Amazon serves publicly, at a deliberately unhurried pace. It is not affiliated with, endorsed by, or connected to Amazon.com, Inc. What you may do with the data it returns depends on where you are and what you use it for, and that is your call to make.