When comparing Redis vs Hazelcast, the Slant community recommends Redis for most people. In the question“What are the best scalable In-Memory Databases?” Redis is ranked 1st while Hazelcast is ranked 6th.
Ranked in these QuestionsQuestion Ranking
Pro Redis is written in ANSI C and therefore doesn't have a VM
Pro Good support
Redis has great docs, an active mailing list, and a github community.
Pro Redis uses the BSD license
This means that it is able to be used in a commercial product if one wants.
Pro There are numerous client libraries and frameworks to make redis more powerful
For Node.JS for example you can get something similar to what Parse.com was offering by using Node ORM.
Pro Good documentation
Hazelcast's documentation is excellent, they have a full javadoc and very in-depth guides for performance tuning and all the bells and whistles of the framework.
Pro Open source
Hazelcast is a free and open source software released under the Apache 2 license.
Pro Cross platform clients
Pro 24/7 professional support available
Hazelcast has 24/7 professional support available for open source users.