Azure Cosmos DB for NoSQL vs JayDB

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.

JayDB is a JSON document database with per-user sign-in, aimed at static apps that need user, session, or tenant data without an app-owned backend. Documents are JSON at slash-separated paths, and the first write creates the namespace. Its REST data plane supports GET, PUT, DELETE, and prefix listing. Browser apps can authenticate through OIDC with Authorization Code and PKCE without embedding a client secret. Listed identity providers include Google, GitHub, Microsoft, generic OIDC, and custom OAuth2. The official SDK supports authentication, token refresh, typed document access, and compare-and-swap operations. ETag-based compare-and-swap may reject a write with HTTP 412 if the document changed since it was read. JayDB is available as managed cloud software or as a self-hosted Go engine under the MIT license, using S3-compatible storage or local disk. The free plan is free and includes 1 GB stored, 100,000 reads per month, and 10,000 writes per month; usage hard-stops at those allowances. Metered rates are $0.05 per GB-month of storage, $0.20 per million reads, and $0.50 per million writes.