NoSQL Data Modeling Techniques 

Redis (REmote DIctionay Server) is a very popular open-source, networked, in-memory, key-value data store, sometimes referred to as a data structure server which also comes with optional durability. Redis is well known for high performance, flexibility, provides a rich set of data structures, and a simple straightforward API.  

Overall I was very very happy with LiteDB and I particularly like the fact that is was free, and it did pretty much exactly the same as RavenDB Emebedded (sometimes it was easier to do as well). 

How Leading NoSQL Databases Compare Across the Eight Core Requirements

Like many other modern JSON databases, RethinkDB is schemaless: the developer doesn’t have to define a fixed structure or specify field types when creating a new table. In cases where validation is desirable, it’s up to the developer to build it into their application. 

Role of NoSQL Databases in Modern Applications