Cosmos DB
A globally distributed multi-model database service on Microsoft Azure with property graph support through the Apache Gremlin API. Offers multi-region replication and multiple consistency models.
- Overall rank
- #16
- First released
- August 2014
- License
- Proprietary
- Built with
- C++
Sources 8 references
Protocols Gremlin (WebSocket), HTTP/REST, Native binary
Gremlin API is WebSocket (confirmed by the 101-upgrade error path in the Gremlin FAQ) and the default access mode for all APIs is an HTTPS gateway (HTTP/REST); rejected pass_B's justification for Native binary (Cassandra/MongoDB wire compatibility, which explicitly reuse standard, non-proprietary protocols the vocabulary has no tag for) but added Native binary anyway for a different, undisputed reason neither pass raised: the SQL/Core API's proprietary TCP 'direct mode', which only the .NET and Java SDKs support and which Microsoft does not publish a wire spec for; the port table shows direct mode is not offered for the Graph API.
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A Gremlin connection is made through a WebSocket connection.
Frequently asked questions - Azure Cosmos DB for Apache Gremlin | Microsoft Learn · reviewed 2026-08-02 -
The Azure Cosmos DB REST API provides programmatic access to Azure Cosmos DB resources to create, query, and delete databases, document collections, and documents.
Azure Cosmos DB REST API Reference · reviewed 2026-08-02 -
Additionally, it offers an efficient TCP protocol, which is also RESTful in its communication model and uses TLS for initial authentication and encrypting traffic, called direct mode.
SQL SDK Connectivity Modes - Azure Cosmos DB | Microsoft Learn · reviewed 2026-08-02
License Proprietary
Confirms the current value. Cosmos DB is a closed-source, commercially licensed Microsoft cloud service; no source or license file is published.
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Azure Cosmos DB is a fully managed, cloud-native NoSQL database designed to deliver ultra-low latency and elastic scalability at a global scale.
Azure Cosmos DB | Microsoft Azure · reviewed 2026-08-02 -
Written in C++ Supported Languages C#, Go, Java, JavaScript, Python Operating System Windows License Proprietary
Cosmos DB · Database of Databases · reviewed 2026-08-02
Released 2014-08
Corrected from 2017-05. That date is Cosmos DB's rebrand/GA, but Microsoft's own account is that the same underlying engine ("Project Florence", 2010) first reached the public as Azure DocumentDB, in preview, in August 2014; DocumentDB became generally available in 2015 and was renamed/expanded into Cosmos DB in May 2017. Treated as a rename per the brief's guidance rather than a new product.
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I’m excited to announce the preview of our new DocumentDB service - a NoSQL document database service designed for scalable and high performance modern applications.
Azure: New DocumentDB NoSQL Service, New Search Service, New SQL AlwaysOn VM Template, and more · reviewed 2026-08-02 -
Azure Cosmos DB started as “Project Florence” in late 2010, which eventually grew into Azure DocumentDB before expanding and blossoming into its current form.
A technical overview of Azure Cosmos DB · reviewed 2026-08-02
Language C++
No primary Microsoft source discloses the implementation language of this closed-source service. Only a third-party database encyclopedia was found; treat as a lead rather than a confirmed fact.
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Written in C++ Supported Languages C#, Go, Java, JavaScript, Python Operating System Windows License Proprietary
Cosmos DB · Database of Databases · reviewed 2026-08-02