Usually the results from various Elasticsearch APIs are displayed in JSON format. But JSON is not easy to read always. So CAT APIs feature is available in Elasticsearch helps in taking care of giving an easier to read and comprehend printing format of the results. There are various parameters used in cat API which serve different purpose, for example – the term V makes the output verbose.
Show each index and their details
nodes command shows the cluster topology
Show health status of each index
plugins command provides a view per node of running plugins.
count provides quick access to the document count of the entire cluster, or individual indices.
GET /_cat/count/<target> //v, the response includes column headings. Defaults to false. GET /_cat/count/users?v