Cayley vs Titan: What are the differences?
Cayley: An open-source graph database. Cayley is an open-source graph inspired by the graph database behind Freebase and Google's Knowledge Graph. Its goal is to be a part of the developer's toolbox where Linked Data and graph-shaped data (semantic webs, social networks, etc) in general are concerned; Titan: Distributed Graph Database. Titan is a scalable graph database optimized for storing and querying graphs containing hundreds of billions of vertices and edges distributed across a multi-machine cluster. Titan is a transactional database that can support thousands of concurrent users executing complex graph traversals in real time.
Cayley and Titan can be primarily classified as "Graph Databases" tools.
Cayley is an open source tool with 12.6K GitHub stars and 1.12K GitHub forks. Here's a link to Cayley's open source repository on GitHub.