AllegroGraph is described as 'high-performance, persistent graph database. AllegroGraph supports SPARQL, RDFS++, and Prolog reasoning from numerous client applications' and is an app in the Development category. There are eight alternatives to AllegroGraph for a variety of platforms, including Linux, Mac, Windows, Online / Web-based and BSD. The best alternative is neo4j, which is both free and Open Source. Other great apps like AllegroGraph are GraphStack.io (Free, Open Source), RedisGraph (Free, Open Source), NetworkX (Free, Open Source) and LemonGraph (Free, Open Source).
RedisGraph is a property graph database module for Redis. It is the first graph database to use linear algebra on sparse adjacency matrices to implement graph operations, which lets it achieve high performance. It understands OpenCypher queries.