AWS claims to be a native graph DB.
It would be interesting to see performance comparisons with Neo4j and similar native graph DBs.
Amazon Neptune Generally Available | AWS News Blog
Amazon Neptune - Fast, Reliable Graph Database built for the cloud
AWS re:Invent 2017 - Amazon Neptune: Fast, Reliable Graph Database Built for the Cloud - YouTube
Amazon Neptune vs. Neo4j Comparison
Amazon Neptune vs. Microsoft Azure Cosmos DB Comparison
Welcome to the Graph Community, Amazon Neptune! by Neo4j founder and CEO
Azure Cosmos DB Costs vs Dynamo DB and Neptune - Thomas LaRock
Cost Comparison: Azure Cosmos DB vs. DynamoDB vs. Neptune - DZone Database
Amazon Neptune, a New Cloud Graph Database, Is Now Generally Available @ InfoQ