Amazon Keyspaces vs Azure Cosmos DB for NoSQL

Amazon Keyspaces is a managed database service compatible with Apache Cassandra. It is serverless, requires no infrastructure management, and scales automatically with application demand. The service supports the Cassandra Query Language API, existing application code, Cassandra drivers, and developer tools. Tables can use on-demand read and write capacity or provisioned capacity with optional auto scaling. AWS describes single-digit-millisecond read and write performance, with no limit on table size or row count. Multi-Region deployments offer up to 99.999% availability, and table data is replicated three times across multiple Availability Zones. Keyspaces integrates with CloudWatch for performance metrics and can stream changes to Amazon OpenSearch Service. Keyspaces Streams provides change data capture, while point-in-time recovery can restore table data to any second in the preceding 35 days. Data is encrypted at rest by default, with AWS-owned or customer-managed keys. The free tier lasts for the first three months after creating the first resource, is limited to one per payer account, and includes 30 million write request units, 30 million read request units, and 1 GB of storage.

Azure Cosmos DB for NoSQL is a fully managed cloud database built around schema-agnostic JSON documents and SQL-like querying. It supports global data distribution, multi-region writes, and automatic failover, with configurable consistency controls and transactions. Search includes vector and hybrid similarity capabilities for workloads such as retrieval-augmented generation and AI agents. Throughput can use standard provisioned, autoscale provisioned, or serverless models. The service lists SDKs for.NET, Java, JavaScript/Node.js, Python, Go, and Rust. Its change feed can support event-driven architectures and streaming pipelines using Azure Functions and Spark; no-ETL analytical workflows are available through Azure Synapse Link or Fabric mirroring. Microsoft states that NoSQL data has service-level agreements including less than 10 millisecond read and write latency and 99.999 percent availability. A free tier includes 1,000 RU/s and 25 GB of storage for one account per Azure subscription, and a 30-day trial is listed. The Azure Cosmos DB emulator provides a no-cost local development environment for Windows or Linux. The pricing page notes that the selected compute pricing model and API cannot be changed after selection.