Azure Cosmos DB is a fully managed NoSQL database service for modern app development. Get guaranteed single-digit millisecond response times and 99.999-percent availability, backed by SLAs, automatic and instant scalability, and open-source APIs for MongoDB and Cassandra.

Amazon DynamoDB is a key-value and document database that delivers single-digit millisecond performance at any scale. It's a fully managed, multi-region, multi-active, durable database with built-in security, backup and restore, and in-memory caching for internet-scale applications.

DynamoDB differs from other Amazon services by allowing developers to purchase a service based on throughput, rather than storage. If Auto Scaling is enabled, then the database will scale automatically. Additionally, administrators can request throughput changes and DynamoDB will spread the data and traffic over a number of servers using solid-state drives, allowing predictable performance.

Example Pricing

10M Serverless Request Units ($2,82), 10GB of consumed storage ($2,5), 10 GB of backup storage ($1,5) $6,82USD 

Dynamo DB's prices vary according to region, the provided example utilizes the US East (N. Virginia) prices.

Free Tier

• 25 GB of data storage
  
• 2.5 million stream read requests from DynamoDB Streams
• 1 GB of data transfer out, aggregated across AWS services  
  
  

Example Pricing

Applications with 10M reads ($2,5), 1M writes ($1,25), 1 GB ($0,25) and continuous backup ($0,20) $4,20 USD

​Onboarding
Great documentation to start things off.

​Scalability

Includes the ability to autoscale, with configuration options for it.

Regions

Azure Cosmos DB is available on all the platforms that have Azure available, such as the United States, Europe, Asia Pacific, and more to come.

​Backups 

Azure Cosmos DB automatically takes backups of your data at regular intervals. The automatic backups are taken without affecting the performance or availability of the database operations. Azure Cosmos DB automatically takes a full backup of your database every 4 hours and at any point of time, only the latest two backups are stored by default. If the default intervals aren't sufficient for your workloads, you can change the backup interval and the retention period from the Azure portal.

​Security
If you choose an on-premises solution, you need to provide everything from end-point protection to physical security of your hardware - which is no easy task. If you choose a PaaS cloud database provider such as Azure Cosmos DB, your area of concern shrinks considerably.

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Onboarding
Rich in documentation, with a great tutorial to start things off.

Scalability
Has automatic scaling as an option.

Regions
United States, Africa, Asia Pacific, Europe, Middle East.

To connect programmatically to an AWS service, you use an endpoint. In addition to the standard AWS endpoints, some AWS services offer FIPS endpoints in selected Regions.

Backups 
Charged separatedly from the project. Has three different options: Continuous backups, on-demand, or restoring a table.

Security
AWS is responsible for protecting the infrastructure that runs AWS services in the AWS Cloud. Includes data protection, identity and access management, infrastructure security, and more.

Azure Cosmos DB is a fully managed NoSQL database for modern app development. Single-digit millisecond response times, and automatic and instant scalability, guarantee speed at any scale.

• ​Guaranteed speed at any scale
  
• Fast, flexible app development with SDKs for popular languages, a native Core (SQL) API along with APIs for MongoDB, Cassandra, and Gremlin, and no-ETL (extract, transform, load) analytics
  
• Ready for mission-critical applications
  
• Fully managed and cost-effective serverless database
  
• Serverless database operations
  
• Hybrid platform for Cassandra data
• No-ETL analytics over real-time operational data 
  
  

Amazon DynamoDB is a NoSQL database that supports key-value and document data models. Developers can use DynamoDB to build modern, serverless applications that can start small and scale globally to support petabytes of data and tens of millions of read and write requests per second.

• Microsecond latency with DynamoDB Accelerator
  
• Automated global replication with global tables
  
• Read/write capacity modes
  
• On-demand mode
  
• ACID transactions
• Encryption at rest
  
• Point-in-time recovery
  
• On-demand backup and restore
  

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