Retreive your optiseller keys as per https://help.optiseller.com/en/articles/8255236-getting-started-with-the-optiseller-api

Postman is an API platform for building and using APIs, and allows you to test out APIs without creating any code.

We have created a postman collection to accompany our API. To get started with this, import the collection to Postman - https://learning.postman.com/docs/getting-started/importing-and-exporting/importing-data/

The file to import is attached at the bottom of the article, or the direct URL is https://optiseller.intercom-attachments-7.com/i/o/806978705/81c1eb483ba0776f31f9d352/Optiseller+Getting+Started+%28public%29.postman_collection.json

Once imported, you will see the pre-constructed API requests:

Each request has a set of parameters and headers:

Headers

For the header Ocp-Apim-Subscription-Key, you should enter your Optiseller API key.

And, depending on the request, you can enter the parameters required. In this example, we are looking to categorise based on an EAN for the eBay_GB marketplace, and filtering on Medium or higher confidence results

And after clicking "send" we can see the results in postman