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 indices

Show each index and their details 

GET /_cat/indices?v

Show nodes

The nodes command shows the cluster topology

GET /_cat/nodes?h=ip,port,heapPercent,name

Show health

Show health status of each index

GET /_cat/health?v

Show plugins

The plugins command provides a view per node of running plugins.

GET /_cat/plugins?v&s=component&h=name,component,version,description

Show count

Th 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