Introduction to Azure Cosmos DB Graph APIs | Microsoft Docs
"Azure Cosmos DB can be queried using Apache TinkerPop's graph traversal language, Gremlin, and integrates with other TinkerPop-compatible graph systems."
Build an Azure Cosmos DB .NET application using the Graph API | Microsoft Docs
Not to be confused with "Microsoft Graph API" that is superset of Azure AD and O365 APIs.
Overview - Documentation - Microsoft Graph
Also not to be confused with new Graph features in SQL Server 2017
SQL Graph Architecture | Microsoft Docs
It will be interesting to see performance comparisons with native Graph databases like Neo4j
Usually to keep high performance graph databases run on single node with very large memory...
Microsoft so far implemented Gremlin language, while Neo4j has very good Cypher query language.