ArangoDB

ArangoDB is a multi-model database engine that stores data as documents, as graph edges and nodes, or as plain key/value pairs, and queries all three through a single query language called AQL. Transactions are ACID across models, and joins between document collections and graph traversals can run in one pass instead of copying data between separate engines.

Teams use it for catalogues, recommendations, identity graphs, and configuration data where the shape of relationships changes as often as the records do.

Deploying it yourself keeps every node and edge inside your network, without per-seat licensing or vendor lock-in.