I think the best open-source graphdb, also used for Amazon Neptune, is blazegraph [1]
For true data interoperability, as opposed to the silo data models required for property graph databases, the RDF w3c standard with SPARQL [2] is the industry standard. The new global API made possible with the Solid project [3] by Tim Berners-lee uses RDF
For true data interoperability, as opposed to the silo data models required for property graph databases, the RDF w3c standard with SPARQL [2] is the industry standard. The new global API made possible with the Solid project [3] by Tim Berners-lee uses RDF
[1] https://blazegraph.com/ [2] https://en.wikipedia.org/wiki/SPARQL and https://www.w3.org/TR/sparql11-query/ [3] https://solidproject.org/