The list is alphabetical order.

AliExpress

Open Platform: https://developers.aliexpress.com/en/doc.htm?docId=121124&docType=1

Amazon

Selling Partner API: https://developer-docs.amazon.com/sp-api/docs

eBay

eBay APIs: https://developer.ebay.com/develop/apis

Etsy

Etsy Open API v3: https://developers.etsy.com/documentation

Mercado Libre

API Docs: https://developers.mercadolibre.com.ar/en_us/introduction-products

Mercari (Japan)

mercari shops API: https://api.mercari-shops.com/docs/index.html

They only provide API to developers who have contract with Mercari.

Rakuten

Rakuten Search APIs: https://webservice.rakuten.co.jp/documentation

Rakuten only provides search APIs.

Shein

SHEIN Open Platform: https://openapi-portal.sheincorp.com/

Need US, MX, BR, THA or CN mobile number to receive a verification code during signup.

Temu

No API provided.

TikTok

TikTok Shop Partner Center Developer Guide: https://partner.tiktokshop.com/docv2/page/64ec52df9495ef0281398e5a

Walmart

Walmart Marketplace API: https://developer.walmart.com/home/us-mp/

Yahoo Shopping (Japan)

Yahoo Shopping API: https://developer.yahoo.co.jp/webapi/shopping/ (Japanese)