Adding or updating customers programmatically via the Laudspeaker API
upsert endpoint is designed to allow Luadspeaker users the programmatic ability to add new customers or update existing customers.
The upsert endpoint looks up a customer document using the supplied primary_key, and then adds or changes customer attribute values specified in the properties json object in the request body.
Api-Key followed by the API key, for example Api-Key M4jxXt6diYz1Dds1YmhHe93KGPAUi24PlXgaiRXi.null.