In version 2.0 of MailChimp’s API, there was a helper/ping endpoint, which is useful for automated monitoring (e.g. Nagios checks.)
This no longer exists in v3.0, which is quite a bit different.
Just to share the recommendation their API support team gave me, use the API Root resource instead, and assuming you don’t need all the data it returns, just append
?fields=account_name and it will only send that specific field back.
I’d recommend logging the HTTP response code too and checking it’s 200, e.g. in PHP:
$http_status = curl_getinfo( $ch, CURLINFO_HTTP_CODE );