Hazelcast is described as 'in-memory Open Source data grid based on Java. By having multiple nodes form a cluster, data is evenly distributed among the nodes. Thllows for horizontal scalability both in terms of available storage space and processing power' and is an app in the Development category. There are more than 25 alternatives to Hazelcast for a variety of platforms, including Linux, Windows, Mac, Online / Web-based and BSD. The best alternative is MongoDB, which is free. Other great apps like Hazelcast are Redis (Free, Open Source), CouchDB (Free, Open Source), RethinkDB (Free, Open Source) and Cloudify (Free, Open Source).
MongoDB is a document database with the scalability and flexibility that you want with the querying and indexing that you need MongoDB stores data in flexible, JSON-like documents, meaning fields can vary from document to document and data structure can be changed over...
Redis (REmote DIctionary Server) is an open-source, networked, in-memory, key-value data store with optional durability. It is often referred to as a data structure server since keys can contain strings, hashes, lists, sets and sorted sets.
Apache CouchDB is a distributed, fault-tolerant and schema-free document-oriented database accessible via a RESTful HTTP / JSON API. It includes incremental map / reduce mechanics for queries and keeps data safe with an append-only datastore.
RethinkDB pushes JSON to your apps in realtime. When your app polls for data, it becomes slow, unscalable, and cumbersome to maintain. RethinkDB is the open-source, scalable database that makes building realtime apps dramatically easier.
Cockroach is a distributed key/value datastore which supports ACID transactional semantics and versioned values as first-class features. The primary design goal is global consistency and survivability, hence the name.