Amazon Competitor API to Find Comparable Products for an ASIN

What this API returns

The Competitor endpoint takes one ASIN and returns the listings Amazon shoppers are most likely to compare it with, each with the same set of sales, price, review and seller fields. It turns "who am I up against?" into a table you can sort.

A real request for one cat water fountain in the US (ASIN B08NCDBT7Q), asking for 10 rows, returned 9 listings. Four of them:

Every row carries the full product record — revenue, fba, profit, variations, sellers, badge, subcategories, dimensions and weight. The full field list is in the competitor reference.

Request example

curl --request POST \
  --url https://ecommercedataapi.com/v1/amazon/asin/competitor \
  --header "Content-Type: application/json" \
  --header "X-API-Key: ${ECOMMERCE_DATA_API_KEY}" \
  --data '{
    "marketplace": "US",
    "asin": "B08NCDBT7Q",
    "size": 20
  }'

• asin is required; marketplace defaults to US. Supported codes: US, UK, DE, FR, IT, ES, MX, CA, AU, JP, IN, AE, BR.
• size sets how many listings to return, up to 200. You may receive fewer than you ask for — 9 of 10 above.
• One call returns everything; there is no paging.

Reading the result

Three things in that response are worth handling before you analyse it:

• The input ASIN is in the list. Filter it out, or keep it as the baseline row, but do not count it as a competitor.
• Your own brand can appear. Three of the nine rows, including the ASIN itself, were the same brand. For a seller that is cannibalisation, not competition, and it changes the conclusion.
• Neighbouring categories come in. One row was a dog fountain filed under Pet Supplies:Dogs. Check nodeLabelPath if you only want direct substitutes.

Two fields are easy to confuse. units is the modelled monthly estimate (23163 for the ASIN itself). amzUnit is a rounded figure (10000, 7000, 800 in this response), which reads as the lower bound of a "bought in the past month" band rather than a count. Use units to compare, and amzUnit as a sanity check on order of magnitude.

Common workflows

1. Size the competition. Sum units and revenue across the rows to see how much of the niche the top comparable listings take, and how concentrated it is.
2. Find where the sales sit. Sort by price: in the response above, five rows priced $19.99–$27.99 took 90,563 of the 102,327 estimated units, while three rows at $43.99–$63.49 shared 11,680. Price band analysis shows how to read such gaps.
3. See how a newcomer got in. Rows with a recent availableDate and high units are the ones to study. Pull their keywords with the reverse ASIN API and their history with the sales estimate API.
4. Keep a competitor sheet. The competitor analysis template separates what you observed from what you will do about it.

Limits worth knowing

• units, revenue, profit and fba are estimates, not Amazon figures. Competitor analysis explains why a side-by-side table rarely produces an action on its own.
• The list is what shoppers compare with this ASIN, not every product in the category. For a category-wide view, use product research with a nodeIdPath.
• Each successful call consumes one billing unit.

FAQ

How is this different from searching a keyword? A keyword search returns everything that matches the words. The competitor endpoint starts from one product and returns the listings positioned against it, which is closer to how a shopper decides.

Can I get competitors in Japan or Germany? Yes. Set marketplace to JP, DE or any of the 13 supported codes. The ASIN must exist in that marketplace.

Can an AI agent use it? Yes. The endpoint is a tool on the remote MCP server, so an assistant can pull competitors for an ASIN and summarise them in one step.