DynamoDB vs Cosmos DB vs Firestore — NoSQL Databases Compared
Compare AWS DynamoDB, Azure Cosmos DB, and Google Cloud Firestore for managed NoSQL. Pricing models, consistency, and scale.
Feature Comparison
| Feature | Amazon DynamoDB | Azure Cosmos DB | Google Cloud Firestore |
|---|---|---|---|
| Data models | Key-value + document | Multi-model (5 APIs) | Document |
| Global distribution | Global Tables | Multi-region, multi-write | Multi-region |
| Consistency options | Eventual + strong | 5 levels | Strong |
| Serverless pricing | On-demand mode | Serverless tier | Always serverless |
| Real-time sync | AppSync (separate) | Change feed | Built-in |
Service Details
Amazon DynamoDB
Fully managed key-value and document database. Single-digit millisecond performance at any scale with on-demand or provisioned capacity.
- Predictable single-digit ms latency at any scale
- True serverless with on-demand mode
- DAX in-memory caching
- Global tables for multi-region
- 400KB item size limit
- Complex query model (no ad-hoc SQL)
- Can be expensive for scan-heavy workloads
Azure Cosmos DB
Globally distributed multi-model database. Unique multi-API support (SQL, MongoDB, Cassandra, Gremlin, Table) with tunable consistency.
- 5 consistency levels (unique in the industry)
- Multi-API (SQL, MongoDB, Cassandra, Gremlin, Table)
- Global distribution with multi-write regions
- Serverless tier for intermittent workloads
- RU pricing model is unintuitive
- Can be expensive at scale
- Complex cost modeling
Google Cloud Firestore
Serverless document database with real-time sync and offline support. Strong mobile/web client SDKs via Firebase.
- Real-time synchronization
- Excellent mobile/web SDKs (Firebase)
- True serverless (no capacity planning)
- Offline support built-in
- Document-oriented only
- Query limitations (no cross-collection joins)
- Less suitable for high-throughput analytics
When to Use Which
Choose DynamoDB for predictable high-throughput key-value workloads on AWS. Choose Cosmos DB for multi-model, multi-region needs with tunable consistency. Choose Firestore for mobile/web apps needing real-time sync and offline support.
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