Amazon ElastiCache is a web service that makes it easy to deploy, operate, and scale in memory cache in the cloud . It supports two open-source in-memory caching engines:

• Memcached
• Redis

Redis – a fast, open source, in-memory data store and cache > Amazon Elastic cache for Redis is a Redis compatible in-memory  service that delivers the ease-of-use and power of Redis along with the availability, reliability and performance suitable for the most demanding applications.

Using Amazon ElasticCache, you can add an in-memory layer to your infrastructure.