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Databases · head to head

Amazon RDS vs MongoDB

Amazon RDS logo

Amazon RDS

Databases

Set up, operate, and scale a relational database in the cloud

From
Free
Rated
-
Full reviewWebsite
MongoDB logo

MongoDB

Technology

The developer data platform

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Amazon RDS no super-user access or direct host connectivity limits advanced customization; MongoDB 16 MB maximum document size limits large single objects
  • They diverge on capability: Amazon RDS covers Multiple DB Engines, MongoDB covers Document model.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Amazon RDS and MongoDB actually diverge.

Attributes where Amazon RDS and MongoDB differ
AttributeAmazon RDSMongoDB
Pricing modelusage-basedUnknown
PlatformsAWS Cloud, Multi-AZ, Multi-regionCloud (Atlas), Self-hosted, Multi-cloud (AWS, Google Cloud, Azure)
CategoryDatabasesTechnology
Founded20062007

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

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 Amazon RDS

  • Multiple DB Engines
  • Automated Backups
  • Multi-AZ Deployment
  • Read Replicas
  • Performance Insights
  • Automatic Scaling
  • MySQL
  • PostgreSQL

Only in MongoDB

  • Document model
  • Distributed architecture
  • ACID transactions
  • Real-time analytics
  • Full-text search
  • Time series data
  • Geospatial queries
  • Aggregation framework

Both cover

  • Encryption

What people use each for

The jobs each tool is most often brought in to do.

Amazon RDS

  • Transaction processingnot MongoDB
  • Data storagenot MongoDB
  • Application backendnot MongoDB
  • Reportingnot MongoDB
  • Data analyticsnot MongoDB

MongoDB

  • Mobile applicationsnot Amazon RDS
  • Content managementnot Amazon RDS
  • Real-time analyticsnot Amazon RDS
  • IoT applicationsnot Amazon RDS
  • Gaming backendsnot Amazon RDS

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Amazon RDS

  • No super-user access or direct host connectivity limits advanced customization
  • Pricing unpredictable and expensive compared to GCP alternatives with equivalent features
  • Limited access to system procedures and tables requiring advanced permissions
  • No Oracle RAC (Real Application Clusters) support for high-availability Oracle deployments

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

Pricing, plan by plan

Amazon RDS

Free
  • On-Demand Instances$undefined/per second
  • Reserved Instances$undefined/mo
  • Database Savings Plans$undefined/mo

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

Which should you pick?

Choose Amazon RDS if

  • You need multiple db engines.
  • You want to start without paying.
  • You work on AWS Cloud, Multi-AZ, Multi-region.
  • You also want automated backups.
Amazon RDS review

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.
MongoDB review

Questions people ask

Is Amazon RDS or MongoDB better?
Neither clearly leads. Amazon RDS starts at Free and MongoDB at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Amazon RDS or MongoDB?
Amazon RDS starts at Free and MongoDB at Free.
Does Amazon RDS or MongoDB run on more platforms?
Amazon RDS runs on AWS Cloud, Multi-AZ, Multi-region. MongoDB runs on Cloud (Atlas), Self-hosted, Multi-cloud (AWS, Google Cloud, Azure).
Can I use Amazon RDS for free?
Both have a free tier, so you can try either at no cost before committing.
What is Amazon RDS best used for?
Amazon RDS is most often used for transaction processing, data storage, application backend, reporting. Of those, transaction processing and data storage are not what MongoDB is typically brought in for.
What can Amazon RDS do that MongoDB cannot?
Amazon RDS covers Multiple DB Engines, Automated Backups, Multi-AZ Deployment, Read Replicas. MongoDB covers Document model, Distributed architecture, ACID transactions, Real-time analytics. Both handle Encryption.

Answered from the vendors’ own pages

Amazon RDS: What is included in the AWS Free Tier for RDS?

For signups before July 15, 2025: 750 hours per month of single-AZ database instance usage (12 months), 20 GB General Purpose SSD storage monthly, 20 GB automated backup storage monthly, available engines include MySQL, MariaDB, PostgreSQL, SQL Server Express Edition. For signups after July 15, 2025: choice between Free Plan or Paid Plan, $100 in credits plus up to $100 additional credits for activating foundational services, credits valid 12 months. Free Tier unavailable in AWS GovCloud (US) and China (Beijing) regions.

Source
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.

Source
Amazon RDS: How is data transfer priced in RDS?

Same Availability Zone (EC2 to RDS) is free. Multi-AZ replication is free. Cross-AZ within same region is 0.01 USD per GB in and out. Cross-region snapshots and backups follow standard data transfer charges.

Source
MongoDB: 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.

Source
Amazon RDS: What database engines are supported by RDS?

Aurora, MySQL, PostgreSQL, MariaDB, Oracle, SQL Server, and IBM Db2. Pricing varies by engine.

Source
MongoDB: 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.

Source
Amazon RDS: What cost components are included in RDS monthly pricing?

DB instance hours (billed in 1-second increments, 10-minute minimum), storage per GB per month, I/O requests (Aurora and magnetic storage only), provisioned IOPS per month, backup storage, and data transfer fees.

Source
MongoDB: 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
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