AWS Cost Explorer can be used to access custom Reserved Instance purchase recommendation for Amazon Elasticsearch Reservations, Amazon ElastiCache and Amazon Redshift

Reserved instance purchase recommendations can be accessed for Amazon Elastic Cache, Amazon Elasticsearch reservations, and Amazon Redshift through AWS Cost explorer. Reserved instances recommendation can be viewed for Amazon RDS reservations and Amazon EC2. These recommendations can be generated through AWS Cost Explorer by analyzing the usage so identify automatically all the demand usage that can be covered with Reserved Instances for the service mentioned above. Thus Cost Explorer generates Purchase recommendation to cover the on-demand usage at a discounted Reserved Instance rate. You can also programmatically retrieve the recommendation through AWS Cost Explorer API. You can refer the Accessing Reserved Instance Recommendations user guide to get started with the RI purchase recommendations.