Software · head to head
MongoDB vs CosmosDB
CosmosDB
Software
Globally distributed, multi-model database service from Azure
- From
- Free
- Rated
- -
The short version
- Each has a real cost: MongoDB 16 MB maximum document size limits large single objects; CosmosDB autoscale provisioned throughput enforces a minimum of 1,000 RU/s, billed hourly whether or not the database is used
- They diverge on capability: MongoDB covers Document model, CosmosDB covers Global Distribution.
Where they differ
Only the attributes on which MongoDB and CosmosDB actually diverge.
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Unknown).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in MongoDB
- Document model
- Distributed architecture
- ACID transactions
- Real-time analytics
- Full-text search
- Time series data
- Geospatial queries
- Aggregation framework
Only in CosmosDB
- Global Distribution
- Multi-model APIs
- Elastic Scaling
- Five Consistency Levels
- SLA-backed Latency
- Automatic Indexing
- Serverless
- Azure Functions
What people use each for
The jobs each tool is most often brought in to do.
MongoDB
- Mobile applicationsnot CosmosDB
- Content managementnot CosmosDB
- Real-time analyticsnot CosmosDB
- IoT applicationsnot CosmosDB
- Gaming backendsnot CosmosDB
CosmosDB
- Running a globally distributed multi model database on Azurenot MongoDB
- Serving low latency reads and writes from multiple Azure regionsnot MongoDB
- Storing document, key value and graph data behind a managed servicenot MongoDB
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
MongoDB
- 16 MB maximum document size limits large single objects
- No native JOIN support for relational data operations
- Higher memory usage due to storing field names with each document
- Eventual consistency in distributed deployments can cause data stale reads
CosmosDB
- Autoscale provisioned throughput enforces a minimum of 1,000 RU/s, billed hourly whether or not the database is used
- Provisioned throughput is charged in every region the account is replicated to, so multi region accounts multiply the RU bill
- Storage charges cover data, indexes and backups in each replicated region
- Egress out of Azure and between regions is charged, though ingress is free
- The free allowance is one account per Azure subscription, limited to 1,000 RU/s and 25 GB
- RU/s rates vary by region and are only shown through the pricing calculator rather than a flat published rate
Pricing, plan by plan
MongoDB
Free- M0Free
- 512 MB storage
- Learning and exploration
- M2$9/month
- 2 GB storage
- Development and testing
- M5$25/month
- 5 GB storage
- M10+$56.94/month
- Dedicated clusters for production
CosmosDB
Free- Free TierFree
- 1000 RU/s
- 25GB storage
- First 12 months
- ServerlessFree
- Pay per request
- Auto-scaling
- Event-driven workloads
Which should you pick?
Choose MongoDB if
- You need document model.
- You want to start without paying.
- You work on Cloud (Atlas), Self-hosted, Multi-cloud (AWS, Google Cloud, Azure).
- You also want distributed architecture.
Choose CosmosDB if
- You need global distribution.
- You want to start without paying.
- You work on Web, Azure.
- You also want multi-model apis.
Questions people ask
- Is MongoDB or CosmosDB better?
- Neither clearly leads. MongoDB starts at Free and CosmosDB at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, MongoDB or CosmosDB?
- MongoDB starts at Free and CosmosDB at Free.
- Does MongoDB or CosmosDB run on more platforms?
- MongoDB runs on Cloud (Atlas), Self-hosted, Multi-cloud (AWS, Google Cloud, Azure). CosmosDB runs on Web, Azure.
- Can I use MongoDB for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is MongoDB best used for?
- MongoDB is most often used for mobile applications, content management, real-time analytics, iot applications. Of those, mobile applications and content management are not what CosmosDB is typically brought in for.
- What can MongoDB do that CosmosDB cannot?
- MongoDB covers Document model, Distributed architecture, ACID transactions, Real-time analytics. CosmosDB covers Global Distribution, Multi-model APIs, Elastic Scaling, Five Consistency Levels.
Answered from the vendors’ own pages
MongoDB: Does MongoDB offer a free tier?
Yes. MongoDB Atlas offers an M0 free tier with 512 MB storage for learning and exploration, plus paid options starting at $9/month for M2 with 2 GB storage.
SourceMongoDB: Can I self-host MongoDB?
Yes. You can run MongoDB Community Edition on your own servers, or use MongoDB Enterprise Advanced for self-managed production deployments with enterprise features.
SourceMongoDB: What is the maximum document size in MongoDB?
Documents are limited to 16 MB. For documents exceeding this limit, you can use MongoDB's GridFS API to store files larger than the maximum size.
SourceMongoDB: Does MongoDB support ACID transactions?
Yes. MongoDB supports ACID transactions within a single document by default, and multi-document ACID transactions are available for replica sets and sharded clusters in MongoDB 4.0+.
Source