Marketing & CRM
Create a group of contacts or update them if they already exist. Particularly useful for periodic syncs from another contacts database to HubSpot.
Performance is best when batch size is limited to 100 contacts or fewer.
When using this endpoint, please keep in mind that any errors with a single contact in your batch will prevent the entire batch from processing. If this happens, we'll return a 400 response with additional details as to the cause.