List all indexes on ElasticSearch server?

For a concise list of all indices in your cluster, call

curl http://localhost:9200/_aliases

this will give you a list of indices and their aliases.

If you want it pretty-printed, add pretty=true:

curl http://localhost:9200/_aliases?pretty=true

The result will look something like this, if your indices are called old_deuteronomy and mungojerrie:

{
  "old_deuteronomy" : {
    "aliases" : { }
  },
  "mungojerrie" : {
    "aliases" : {
      "rumpleteazer" : { },
      "that_horrible_cat" : { }
    }
  }
}