MongoDB is a serverless, distributed database orientated towards documents, in other words, saving data in BSON documents instead of registries, making it much more expressive and powerful. It's got all the advantages and usages of a relational database, but being more flexible and dynamic.

The MondoDB Atlas is a database on a global cloud created with modern applications in mind, and it's distributed and safe by default, alongside being managed in AWS, Google Cloud and Azure.

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.

Plans

• Shared: Free forever with a M0 cluster, with a 512MB storage capacity, and shared RAM. Also has M2 and M5 versions available with a monthly fee of $9 and $25 respectively. Great for learning and exploring about MongoDB.
  
• Serverless: For serverless applications with a variable traffic that's generally on the lower values. It requires a minimal amount of configuration. Has a free of $0.30 per read, and has extra frees according to the operations you do.
• Dedicated: For production applications that have a sophisticated workload requirement, has advanced configuration controls, with cluster prices ranging from $0.08 to to $33.26/hr.

Example Pricing

Applications with 10M reads ($2.75), 1M writes ($1.25), 1GB storage ($0.25) and 1GB data transfer ($0.015-0.10 according to traffic): $4.3 USD tops.

Example Pricing

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

Onboarding

Great documentation to start off quickly, with a free plan that's very quick to access. Has a wide amount of resources and guides to learn about it.

Scalability

Automatic, and scalable both horizontally (sharding) and vertically.

Regions​

MongoDB Atlas supports  the following regions: Americas, Asia Pacific, Europe, Middle East and Africa. The choice of cloud provider and region affects network latency for clients accessing your database deployment and the cost of running the database deployment. For clusters, this choice also affects the configuration options for the available cluster tiers. The region refers to the physical location of your MongoDB database deployment.

Backup

​MongoDB Atlas, the official MongoDB cloud service, provides 2 fully-managed methods for backups:

• ​Continuous Backups, which take incremental backups of data in your cluster, ensuring your backups are typically just a few seconds behind the operational system. Atlas continuous backups allow you to restore from stored snapshots or from a selected point in time within the last 24 hours. You can also query a continuous backup snapshot.
• Cloud Provider Snapshots, which provide localized backup storage using the native snapshot functionality of the cluster's cloud service provider.

Security

​MongoDB provides various features, such as authentication, access control, encryption, to secure your MongoDB deployments. Some key security features include: Authentication, SCRAM, Role-Based Access Control, Transport Encryption, among others.

​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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MongoDB is a document database with the scalability and flexibility that you want with the querying and indexing that you need. MongoDB’s document model is simple for developers to learn and use, while still providing all the capabilities needed to meet the most complex requirements at any scale. 

• Rich on JSON Documents
• Allows arrays and nested items as values
• Rich and expressive consulting language
• Filter and order on any field, regardless of the way it's inserted in the document
• Full ACID transactions
• Allows for combinations on inquiries
• Completely automatized
• Security Copy
• Global Clusters

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