Practically all Zenvia Conversion's API operations support downloading the information in CSV format to be used directly in Excel or similar tools. 

To do so, open the URL of the API operation in a browser and include &format=csv within the URL.

An example URL might be:

http://api.zenvia.com/v1/prospects/?api-key=XXXXXXXXXX&format=csv

This way the response will automatically be generated in CSV format and you will be able to download the file directly from your browser.