API key
All API calls require theapi_key parameter. You can find your API Key in the Kit developer settings page under the V3 Key section.

API secret key
Some API calls require theapi_secret parameter. All calls that require api_key also work with api_secret, there’s no need to use both. This key grants access to sensitive data and actions on your subscribers. You should treat it as your password and shouldn’t use it in any client-side code (usually that means JavaScript).
This can also be found in the Kit developer settings page under the V3 Key section.
