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Compare Microsoft technologies
Pick up to four. The comparison starts by saying whether they compete, work together or sit in different layers, then lines up their verified facts. It never names a universal winner.
How they relate
Azure SQL and Azure Cosmos DB can be compared as alternatives for some goals.
From the published profiles: documented as alternative approaches.
Side by side
| Fact | Azure SQL | Azure Cosmos DB |
|---|---|---|
| Type | Cloud service | Cloud service |
| Layers | Data & analytics, AI models & platform | Data & analytics, AI models & platform |
| What it is | Azure SQL is Microsoft's family of SQL Server engine services on Azure: Azure SQL Database for cloud applications (with Hyperscale and serverless options), Azure SQL Managed Instance for near-complete SQL Server compatibility, and SQL Server on Azure Virtual Machines for full OS and engine control. | Azure Cosmos DB is a fully managed NoSQL and vector database for applications that need low latency, elastic scale and global distribution. It offers multi-region writes with a 99.999% availability SLA, built-in vector and hybrid search, and serverless or provisioned throughput billed in request units. |
| Who needs it | Teams moving SQL Server applications to Azure, developers building new relational applications or multitenant SaaS products with many databases, and organizations that want retrieval-augmented generation over relational data without a separate vector store. DBAs who need OS access, specific SQL Server versions or full engine control choose SQL Server on Azure VMs. | Developers building always-on or internet-scale applications such as online retail, IoT telemetry, gaming, personalization and booking systems, and teams building AI agents that need conversation history and vectors next to operational data. Microsoft lists flexible-schema, latency-sensitive, highly elastic, high-throughput and mission-critical workloads as good fits. |
| What it is not | Azure SQL is not a resource you create; you create a SQL database, a managed instance or a SQL Server VM. SQL database in Microsoft Fabric is distinct from Azure SQL Database even though it uses the same engine. Azure SQL is not a globally distributed NoSQL store; for that pattern Microsoft points to Azure Cosmos DB. The PaaS options do not support every SQL Server feature (CLR, for example, is not supported in SQL Database), and compatibility with older SQL Server versions is handled only through database compatibility levels. | Cosmos DB is not an analytics database: Microsoft calls it a poor fit for OLAP workloads and points to Microsoft Fabric. Microsoft also calls it a poor fit for highly relational apps, where it suggests Azure SQL or Azure Database for MySQL. Azure DocumentDB (formerly Cosmos DB for MongoDB vCore) is a different service with a scale-up vCore model and a 99.995% SLA. The 99.999% availability figure applies to multi-region accounts, not to every deployment. |
| Prerequisites |
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| Runs on | Azure SQL Database (PaaS), Azure SQL Managed Instance (PaaS in your virtual network), SQL Server on Azure VMs (IaaS, Windows or Linux) | Azure regions, single or multi-region, Serverless or provisioned throughput, Cosmos DB in Microsoft Fabric, Local emulator for development |
| Availability and licensing | Generally available. Microsoft's Azure SQL overview says SQL Database prices start from $5 per month for the Basic tier (checked 26 Oct 2026). The free tier gives each database 100,000 vCore seconds, 32 GB of data and 32 GB of backup storage per month for the life of the subscription, up to 10 databases per subscription, without an SLA. SQL Server 2025 became generally available at Ignite 2025. Vector indexes are still preview in SQL Server 2025 and in Managed Instance on the SQL Server 2025 update policy. | Generally available. The lifetime free tier gives 1,000 RU/s and 25 GB of storage per account; Microsoft states reserved capacity discounts of up to 63% (checked 26 Oct 2026). Multi-region accounts carry a 99.999% availability SLA. At Ignite 2025 Azure DocumentDB, previously Azure Cosmos DB for MongoDB (vCore), became generally available as a separate product with up to 99.995% availability, and Cosmos DB in Fabric became generally available as part of Microsoft Fabric databases. |
| When something simpler is enough | If your data is document-shaped and needs single-digit millisecond access worldwide with multi-region writes, Azure Cosmos DB fits better. If your team has standardized on PostgreSQL, Azure Database for PostgreSQL avoids changing engines. For development and proofs of concept, the Azure SQL Database free tier (which has no SLA) may be all you need. | If your data is highly relational, with joins and transactions across many tables, Azure SQL or Azure Database for PostgreSQL is simpler. If you are moving a MongoDB application and need deep aggregation and multi-document transaction fidelity, or portability across clouds, Microsoft points to Azure DocumentDB. For a single-region app with modest traffic, a relational database may be easier to model and to budget. |
| Last reviewed | 26 Oct 2026 | 26 Oct 2026 |
| Official resources | Product page (opens in a new tab)Documentation (opens in a new tab) | Product page (opens in a new tab)Documentation (opens in a new tab) |
Each value comes from the technology's profile, where every statement links to its source. Pricing, benchmark and compatibility claims are not shown unless a profile documents them.
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