Azure DocumentDB
activeby Microsoft · since 2023 · also known as Azure Cosmos DB for MongoDB (vCore), vCore-based Azure Cosmos DB for MongoDB
Microsoft's managed MongoDB-compatible service, built on the open-source DocumentDB engine.
Overview
Azure DocumentDB is Microsoft's managed, vCore-priced, MongoDB-compatible document database. It was previously sold as vCore-based Azure Cosmos DB for MongoDB and was renamed at general availability on 18 November 2025. It runs the MIT-licensed DocumentDB engine (PostgreSQL plus BSON extensions), not MongoDB code, and claims about 99% MongoDB API compatibility. It includes integrated vector search, a free tier and automatic sharding once data grows large. Microsoft positions it for scale-up workloads with rich aggregation, and keeps Cosmos DB for globally distributed scale-out work, so the choice between the two matters.
Strengths & trade-offs
Strengths
- +Predictable vCore pricing instead of request units
- +Engine is open source, so you can run the same thing locally or on another cloud
- +Integrated vector search, including on the free tier
- +Strong aggregation-pipeline and multi-document transaction fidelity
- +Entra ID, Azure Monitor and Private Link integration
Trade-offs
- −99.995% SLA and regional deployment, below Cosmos DB's multi-region 99.999%
- −Compatibility is high but not complete; test edge-case operators
- −Naming history (Cosmos DB for MongoDB vCore vs RU) causes confusion in docs and tooling
- −Azure-only as a managed service
Great for
- +MongoDB migrations to Azure without SSPL
- +Content management and catalog backends with complex aggregations
- +RAG applications storing embeddings next to documents
Think twice for
- −Globally distributed multi-region writes (use Cosmos DB)
- −Apps that need features exclusive to MongoDB Atlas
Capabilities
Native or official first-party support · 12 of 25 tracked
Scale & consistency
- Comfortable data size
- Large · ≤ 1 PB
- Horizontal scaling
- Native
- Multi-region
- Read replicas
- Transactions
- Full ACID
- Consistency
- Strong
- Schema
- Schemaless
- Architecture
- Distributed, Primary replica
- Query languages
- MongoDB Query API (MQL), Aggregation pipeline
Vertical scaling first; shards automatically (no shard key needed until multi-TB). Cross-region geo-replicas for DR.
Deployment
available on · Azure
Ecosystem
Alternatives to Azure DocumentDB
Microsoft's globally distributed, multi-API NoSQL and vector database with SLA-backed latency.
azure-documentdb vs azure-cosmos-db →MongoDB's own multi-cloud DBaaS, bundling search, vector search and stream processing.
azure-documentdb vs mongodb-atlas →AWS's managed MongoDB-API database on a proprietary, Aurora-style storage layer.
azure-documentdb vs amazon-documentdb →MIT-licensed, MongoDB-compatible document engine built as PostgreSQL extensions, run by the Linux Foundation.
azure-documentdb vs documentdb-postgres →The default document database: flexible BSON documents, rich queries and built-in sharding.
azure-documentdb vs mongodb →Serverless Postgres with copy-on-write branching and scale-to-zero, now part of Databricks.
azure-documentdb vs neon →Azure DocumentDB FAQ
What is Azure DocumentDB?
Azure DocumentDB is a document database by Microsoft, first released in 2023. Azure DocumentDB is Microsoft's managed, vCore-priced, MongoDB-compatible document database. It was previously sold as vCore-based Azure Cosmos DB for MongoDB and was renamed at general availability on 18 November 2025. It runs the MIT-licensed DocumentDB engine (PostgreSQL plus BSON extensions), not MongoDB code, and claims about 99% MongoDB API compatibility. It includes integrated vector search, a free tier and automatic sharding once data grows large. Microsoft positions it for scale-up workloads with rich aggregation, and keeps Cosmos DB for globally distributed scale-out work, so the choice between the two matters.
Is Azure DocumentDB open source?
No. Azure DocumentDB is proprietary, closed-source software.
Does Azure DocumentDB support ACID transactions?
Yes. Azure DocumentDB supports full ACID transactions, with strong consistency.
Does Azure DocumentDB scale horizontally?
Azure DocumentDB scales horizontally out of the box, with built-in sharding or partitioning. It is comfortable at large scale (≤ 1 PB). It supports cross-region read replicas.
How can I run Azure DocumentDB?
You can use the vendor's managed cloud. It is available on Azure.
What is Azure DocumentDB best for?
Azure DocumentDB is a strong fit for MongoDB migrations to Azure without SSPL; content management and catalog backends with complex aggregations; and RAG applications storing embeddings next to documents. Think twice for globally distributed multi-region writes (use Cosmos DB).
What are the best alternatives to Azure DocumentDB?
Common alternatives to Azure DocumentDB include Azure Cosmos DB; MongoDB Atlas; Amazon DocumentDB; DocumentDB (open-source, PostgreSQL-based); and MongoDB. The right choice depends on your workload, scale and hosting; WhichDB's smart match ranks them against your requirements.
How popular is Azure DocumentDB?
Azure DocumentDB has little measurable public adoption today, so it ranks near the bottom of the WhichDB Score.