Arcadedb

ArcadeDB is an open source multi model database developed by Arcade Data Ltd. A single engine natively stores graphs, JSON documents, key value pairs, full text search indexes, vectors and time series data, with full ACID transactions, so an application that needs several data shapes does not have to run several databases side by side. It suits developers and data teams building applications, including AI and retrieval workloads, that combine graph traversal with document storage and vector similarity. Queries can be written in SQL, OpenCypher, Gremlin or GraphQL, through the MongoDB query protocol, or through a Java API, and each model is native to the engine rather than translated. It runs embedded inside a Java application or as a distributed server, and the free build includes clustering, high availability, vector search and every query language with no node or core limits and no separate enterprise edition. ArcadeDB Studio offers an optional AI assistant that turns natural language into SQL, Gremlin or Cypher and suggests query optimizations. The database is free under the Apache 2.0 license, and the vendor commits to never changing that license. Optional support plans are priced per server: Community is free, Silver is $299 per month, Gold is $599 per month and Platinum is $1,499 per month on monthly billing, with roughly 17 percent off yearly. Each paid plan includes one Studio AI Assistant license, which is otherwise $19.99 per month. Volume licensing and consultancy are quoted on request, and all purchases are non refundable.