Seller fees for 31 marketplaces and payment processors, verified monthly.
Profitvana API is a free Shopping API that requires no API key, is served over HTTPS and supports CORS, so it can be called from the browser.
A free JSON API for marketplace and payment processor fees: 31 platforms, monthly-verified rates, net profit calculation, and a 20-country fee index. No API key, CORS open.
Details from profitvana.com.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Sold resale listings from Poshmark with median price, days to sell and net payout after fees
The Profitvana API is provided by Profitvana (profitvana.com). A free JSON API for marketplace and payment processor fees: 31 platforms, monthly-verified rates, net profit calculation, and a 20-country fee index. No API key, CORS open.
Yes. The Profitvana API is listed in the Shopping category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
No. The Profitvana API requires no authentication, so you can start making requests without signing up.
Yes. The Profitvana API supports CORS, so front-end JavaScript can call it directly.
Yes. The Profitvana API is served over HTTPS, so it's safe to use in production.