LevelDB is a fast key-value storage library written at Google that provides an ordered mapping from string keys to string values. 

LiteDB on Xamarin Forms as an Alternative to SQLite 

User authentication in Asp.NET MVC using Cassandra and HectorSharp

A lot of people don’t even know what they would use a NoSQL database

MongoDB Stores structured data as a JSON-like documents

.NET and DynamoDB

Amazon DynamoDB is a fully managed NoSQL database service that provides fast and predictable performance with seamless scalability

There are two broad categories of scale-out databases that serve as an alternative to traditional RDBMSs (NoSQL and NewSQL)

Some NewSQL solutions

NewSQL-db-logosVoltDB  (in-memory database) : http://voltdb.com

ClustrixDB (distributed peer-to-peer SQL database) : http://www.clustrix.com

NuoDB (distributed database management) : http://www.nuodb.com

GenieDB (based on MySQL) : http://www.geniedb.com

ScaleArc (SQL traffic manager ) :  http://www.scalearc.com

ScaleDB (MySQL scalability) : http://scaledb.com

Tokutek/TokuDB (MySQL/MariaDB scallability): http://www.tokutek.com

JustoneDB (built upon PostgreSQL) : http://www.justonedb.com

MemSQL (in-memory database) : http://www.memsql.com