Book sold prices including a bare ISBN

ISBN works as a search

You do not need the title. Pass the bare ISBN and it matches the sellers who put it in their listing, which most volume sellers do. Verified 12 October 2026:

An ISBN is precise but thin, because it only finds sellers who typed it. Title and author is broader. Running both and merging is usually the right answer for a cataloguing tool.

curl -G https://api.compsapi.com/v1/sold \
  -H "Authorization: Bearer YOUR_KEY" \
  --data-urlencode "q=charizard psa 10" \
  --data-urlencode "days=1095" \
  --data-urlencode "best_offer=1"

Asking price is not the market

Book marketplaces are full of listings priced at what a seller hopes for, sitting unsold for years. A completed sale is the only honest signal, and on eBay a large share of book sales close through accepted offers, where the public sold page shows the asking figure rather than the paid one. We return what was actually paid.

Condition is in the title, so filter on it

First edition, signed, ex library and book club copies are different markets for the same ISBN. Use minus words to separate them: Dune Frank Herbert first edition -book+club -ex-library. Keeping the search short matters, because every term has to appear in the seller's title.

Three years of history

Book values move slowly and seasonally, textbooks especially. Ninety days of sales around a single semester will mislead you. Growth and above page the full 1,095 days.