The Karma API is extremely simple. Send the IP you want to query, and receive a plan list of feeds in which the IP is listed.
$ curl https://karma.securetia.com/api/ip/22.214.171.124 alienvault_malicious spamhaus_drop talos
By default, the API returns a plain list, because it's easy to parse with a lot of commands and languages.
If you want a JSON response, simply add the 'application/json' accept header to your request, like this:
$ curl -H "Accept: application/json" https://karma.securetia.com/api/ip/126.96.36.199 [ "alienvault_malicious", "talos", "spamhaus_drop" ]