Amazon Buy Box
Tracked on your schedule, with a signed webhook the instant we catch a change. Push-based and ready to act on, no polling loop, no diffing snapshots yourself.
25 Markets · No Seller Account Required
Buy Box Change
What Determines Who Wins the Amazon Buy Box
The Buy Box is the featured offer on an Amazon product page, the one “Add to Cart” button most shoppers actually click. Amazon doesn’t award it to the lowest price alone. A handful of factors combine to decide it, and any one of them shifting can flip ownership:
- Price
- The total landed price, item plus shipping, not just the listed price.
- Fulfillment method
- FBA listings are generally favored over FBM for delivery speed and reliability.
- Seller performance metrics
- Order defect rate, cancellation rate, and late shipment rate all factor in.
- Stock availability
- A seller who is out of stock cannot hold the Buy Box, regardless of price.
- Account health and tenure
- Newer or lower-health accounts are disadvantaged even at matching price and fulfillment.
- Delivery speed
- The estimated delivery date to a specific buyer, which can differ between sellers using the same fulfillment method depending on warehouse proximity and carrier speed.
Because eligibility depends on more than price, a Buy Box loss can happen with your price unchanged, which is exactly why watching ownership directly, not inferring it from price alone, catches changes a pure price tracker would miss.
What You Get
Ownership, Price, and the Change Event
Who holds it right now
Every response includes the current Buy Box owner, owner ID, seller type (FBA/FBM), and the exact winning price, not just an aggregate price range.
The moment it flips
Subscribe an ASIN and get a signed webhook as soon as a change is caught on your next scheduled check, no need to diff snapshots yourself.
No seller account required
kwery reads the public product page a shopper sees, the view SP-API deliberately withholds for competitor listings. Full competitive visibility, no seller registration.
How It Works
Every ASIN, Checked on Your Schedule
Send an ASIN or GTIN once to subscribe it. From then on, kwery checks it on your schedule and pushes a signed event to your webhook once a change is confirmed, you set how often that check runs.
Subscribe an ASIN or GTIN
Subscribe an ASIN or GTIN, codes resolve to the correct ASIN per marketplace automatically, with no pre-matching table on your side.
kwery checks it
kwery checks it on your schedule: proxy rotation, session handling and CAPTCHA solving are fully abstracted behind the endpoint.
Get notified on change
Get notified on change, a signed webhook fires with the new owner, the new price, and exactly which fields moved.
{
"event": "buybox.change",
"delivered_at": "2026-09-14T14:22:03.000Z",
"product": {
"source": "amazon",
"country": "de",
"key": "asin",
"value": "B0DGHP6V8V",
"name": "Apple iPhone 16 128 GB"
},
"changes": {
"buybox.seller_name": { "old": "Amazon", "new": "Third Party GmbH" },
"buybox.price": { "old": 839.00, "new": 829.90 }
}
}API Response Fields
Ownership, Not Just Price
Buy Box–specific fields. The full product and offer schema is documented on the Amazon API page →
buybox.seller_name · buybox.seller_id · seller_type
Who holds the featured offer right now, per marketplace, the field repricers key on.
buybox.price · shipping
The exact price and shipping cost at which the current owner holds the Buy Box.
fulfillment · stock_status · availability
The levers that explain why ownership might shift, alongside the ownership itself.
changed_fields · previous · current · detected_at
Every webhook event carries both states, so you never diff snapshots yourself.
Try It
Ready to try it against your own ASIN list?
Start free with 1.000 one-time credits. No credit card required.
Who It's For
Repricers, Brand Protection, and PPC Teams
Amazon repricers
Trigger a repricing decision as soon as a Buy Box loss is caught, not on your next scheduled price check.
Feeds → repricer inbound
Brand & MAP monitoring
Watch seller identity and observed Buy Box price, then let your own policy system decide whether the observation needs review.
Feeds → policy review
PPC / advertising teams
Ad spend is largely wasted on a listing that doesn’t hold the Buy Box. Pause campaigns automatically when ownership is lost, resume when it’s regained.
Feeds → campaign automation
Self-Serve
One Credit. One Watched ASIN
Buy Box state, ownership changes, and price, billed the same as any resolved SKU. On Amazon, 1 credit returns 2 full data sets (search + product + offers, matched, each).
Subscribe
GTIN or ASIN resolution, per marketplace.
Watch
Ownership and price checked on your schedule.
Notify
A signed webhook on every real change.
Entry Price
€79 / mo
Included
10k credits / mo
Included Usage
Up to 20k SKUs / mo
Amazon, Walmart & ebay count 2 SKUs per credit. Every other source counts 1.
Free tier available · 1.000 one-time credits, no credit card required.
Enterprise
Need Custom Pricing, SLAs, or Support?
Dedicated volume pricing, custom SLAs, and direct engineering support for teams running millions of SKUs.
Talk to SalesSupport
Common Questions
What people actually ask about the Buy Box, and what teams want to know before tracking changes. General Amazon integration questions (marketplaces, anti-bot handling, GTIN input) are answered on the Amazon Price Tracker FAQ →
Browse all FAQsYes. Use condition, is_direct, total and trust.flagged_offers. The buybox field follows each marketplace's own rule (on Walmart it is the lowest-priced offer of any condition), not what qualifies for you.
The Buy Box is the featured “Add to Cart” offer on an Amazon product page, the one most shoppers click without ever seeing the full list of competing sellers. On a listing with multiple sellers, only one holds it at a time.
No single factor guarantees it. Price, fulfillment method, seller performance metrics, stock availability, and account health all combine, see the full breakdown above. What Determines Who Wins the Amazon Buy Box →.
A signed webhook fires as soon as a scheduled check detects the change, you're not gated by a fixed daily refresh; check frequency is on your schedule.
Yes, every change event includes the winning seller's identity and price, so you can flag an unauthorized seller winning below your minimum advertised price.
Ad spend on a listing that isn't winning the Buy Box is largely wasted, since the featured offer is what most ad clicks convert against. Subscribing your ASINs lets you pause or adjust campaigns as soon as a change is caught.
Push-based, subscribe an ASIN once, and a webhook fires only when something changes. No polling loop to build or diff yourself.
Catch a Buy Box Loss Today
Start tracking Amazon Buy Box ownership today. Free tier available, no seller account required.