Crux is described as 'open source document database with bitemporal graph queries' and is an app in the Development category. There are seven alternatives to Crux for a variety of platforms, including Mac, Windows, Linux, Online / Web-based and BSD. The best alternative is MongoDB, which is free. Other great apps like Crux are neo4j (Free, Open Source), Datomic (Freemium), Datahike (Free, Open Source) and MarkLogic (Paid).
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...
Datahike is a durable Datalog database powered by an efficient Datalog query engine. This project started as a port of DataScript to the hitchhiker-tree. All DataScript tests are passing, but we are still working on the internals.
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.