Special web service exists for it: http://localhost:9200/_cat/indices
It should return list looking like:
yellow open test_index 1 1 0 0 115b 115b yellow open nested_object 5 1 5 0 3.6kb 3.6kb yellow open players 5 1 0 0 575b 575b yellow open parent_child 5 1 6 0 8.3kb 8.3kb yellow open orders 5 1 6 0 11.9kb 11.9kb yellow open waitingforcode 5 1 5124 0 757.5kb 757.5kb