Manage shop and interact with listings.
Etsy API is a free Shopping API that requires OAuth authentication, is served over HTTPS and has unconfirmed CORS support.
Welcome to the improved Etsy Open API v3, a REST API that extends support for inventory, sales orders, and shop management on the Etsy platform. These guides support current and future app developers as they build tools to integrate with and automate processes for Etsy shops and customers.
Details from etsy.com.

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The Etsy API is provided by Etsy Open API v3 (etsy.com). Welcome to the improved Etsy Open API v3, a REST API that extends support for inventory, sales orders, and shop management on the Etsy platform. These guides support current and future app developers as they build tools to integrate with and automate processes for Etsy shops and customers.
Yes. The Etsy 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.
Yes. The Etsy API uses OAuth authentication, so you need to register for credentials before making requests.
CORS support for the Etsy API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Etsy API is served over HTTPS, so it's safe to use in production.