Couchbase is described as 'is the NoSQL database market share leader, with production deployments at AOL, Deutsche Post, NTT Docomo, Salesforce.com, Turner Broadcasting Systems, Zynga and hundreds of other organizations worldwide' and is an app in the Development category. There are more than 50 alternatives to Couchbase for a variety of platforms, including Linux, Windows, Mac, Online / Web-based and BSD. The best alternative is PostgreSQL, which is both free and Open Source. Other great apps like Couchbase are SQLite (Free, Open Source), MongoDB (Free), MySQL Community Edition (Free, Open Source) and MariaDB (Free, Open Source).
NCache has been the market leader in .NET Distributed Caching for the last 13 years. NCache provides an extremely fast and linearly scalable distributed cache that caches application data and reduces expensive database trips.
TayzGrid is an elastic in-memory data grid with a self-healing peer to peer dynamic data grid clustering architecture. TayzGrid is extremely fast and linearly scalable data grid and provides intelligent replication for data reliability without compromising on scalability.
GraphDB is a RDF graph database or triplestore. It is the only triplestore that can perform semantic inferencing at scale allowing users to create new semantic facts from existing facts. It also has the ability to visualize triples.
MarkLogic is the only Enterprise NoSQL database, bringing all the features you need into one unified system: a document-centric, schema-agnostic, structure-aware, clustered, transactional, secure, database server with built-in search and a full suite of application services.