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MongoDB Atlas vs PostgreSQL

MongoDB Atlas logo

MongoDB Atlas

Databases

The multi-cloud developer data platform

From
Free
Free plan
Yes
Visit MongoDB AtlasFull review
PostgreSQL logo

PostgreSQL

Databases

Open source relational database

From
Free
Free plan
Yes
Visit PostgreSQLFull review

The short version

  • PostgreSQL is a powerful, open source object-relational database system.
  • PostgreSQL is free; MongoDB Atlas starts at $0.011/mo.
  • Where MongoDB Atlas falls short: M0 free tier limited to learning and exploration only with no backup capability.
  • Where PostgreSQL falls short: requires manual scaling across multiple machines for very large deployments.
  • Prices and features on this page were last checked on 13 November 2026.

Where they differ

Only the attributes on which MongoDB Atlas and PostgreSQL actually diverge.

Attributes where MongoDB Atlas and PostgreSQL differ
AttributeMongoDB AtlasPostgreSQL
PlatformsWebLinux, Windows, macOS

Identical on both: starting price (Free), free tier (Yes), category (Databases).

Not yet recorded: pricing model for PostgreSQL, founded for MongoDB Atlas.

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 Atlas

Nothing recorded that PostgreSQL does not also cover.

Only in PostgreSQL

  • ACID Compliance
  • JSON/JSONB Support
  • Full-text Search
  • Extensibility
  • Advanced Indexing
  • Partitioning
  • Replication
  • pgAdmin

What people use each for

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

MongoDB Atlas

  • Building applications with flexible JSON document storagenot PostgreSQL
  • Performing full-text and vector search on unstructured datanot PostgreSQL
  • Scaling multi-cloud deployments across AWS, Azure, GCPnot PostgreSQL
  • Streaming event data integration with Kafkanot PostgreSQL

PostgreSQL

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

Where each one falls short

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

MongoDB Atlas

  • M0 free tier limited to learning and exploration only with no backup capability
  • Data transfer egress charges apply at 0.12 USD/GB for dedicated clusters; inbound free
  • MongoDB Search and Vector Search add significant per-hour costs starting at 0.12 USD/hour

PostgreSQL

  • Requires manual scaling across multiple machines for very large deployments
  • Performance tuning requires deep knowledge of database internals
  • No built-in graphical admin interface; command-line tools are primary method

Pricing, plan by plan

MongoDB Atlas

Free
  • M0 (Free Tier)Free
    • 512 MB storage
    • Shared RAM and vCPU
    • No backups
  • Flex Tier$0.011/hour
    • 5 GB storage
    • Shared RAM and vCPU
    • Pay-as-you-go hourly billing
  • M2 Shared$9/mo
    • 2 GB storage
    • Shared RAM and vCPU
  • M5 Shared$25/mo
    • 5 GB storage
    • Shared RAM and vCPU

PostgreSQL

Free

No published plan breakdown. See the PostgreSQL review.

Which should you pick?

Choose MongoDB Atlas if

  • You want to start without paying.
MongoDB Atlas review

Choose PostgreSQL if

  • You need acid compliance.
  • You want to start without paying.
  • You work on Linux, Windows, macOS.
  • You also want json/jsonb support.
PostgreSQL review

Questions people ask

Is MongoDB Atlas or PostgreSQL better?
Neither clearly leads. MongoDB Atlas starts at Free and PostgreSQL at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, MongoDB Atlas or PostgreSQL?
MongoDB Atlas starts at Free and PostgreSQL at Free.
Does MongoDB Atlas or PostgreSQL run on more platforms?
MongoDB Atlas runs on Web. PostgreSQL runs on Linux, Windows, macOS.
Can I use MongoDB Atlas for free?
Both have a free tier, so you can try either at no cost before committing.
What is MongoDB Atlas best used for?
MongoDB Atlas is most often used for building applications with flexible json document storage, performing full-text and vector search on unstructured data, scaling multi-cloud deployments across aws, azure, gcp, streaming event data integration with kafka. Of those, building applications with flexible json document storage and performing full-text and vector search on unstructured data are not what PostgreSQL is typically brought in for.
What can MongoDB Atlas do that PostgreSQL cannot?
PostgreSQL covers ACID Compliance, JSON/JSONB Support, Full-text Search, Extensibility.

Answered from the vendors’ own pages

MongoDB Atlas: How much does MongoDB Atlas cost?

MongoDB Atlas offers a free M0 tier with 512 MB storage, Flex tier at approximately 8-30 USD/month with pay-per-hour billing, shared clusters at 9-25 USD/month, and dedicated clusters from 56.94 USD/month. Add-on services like MongoDB Search cost 0.12-3.27 USD/hour.

Source
PostgreSQL: Is PostgreSQL completely free?

Yes. PostgreSQL is completely free and open source with no licensing fees or restrictions on use.

Source
MongoDB Atlas: Is there a free tier?

Yes, MongoDB Atlas M0 free tier offers 512 MB storage with shared resources, suitable for learning and exploration. Flex tier allows pay-as-you-go usage starting at 0.011 USD/hour.

Source
PostgreSQL: What platforms does PostgreSQL run on?

PostgreSQL runs on all major operating systems including Linux, Windows, macOS, BSD, and commercial Unix variants, and has been proven highly scalable managing terabytes to petabytes of data.

Source
MongoDB Atlas: What are the data transfer limits?

Inbound data transfer is typically free; egress from dedicated clusters costs 0.12 USD/GB. Free and Flex tiers do not incur data transfer charges.

Source
PostgreSQL: What procedural languages are supported?

PostgreSQL supports stored functions and procedures in multiple languages including PL/pgSQL, Perl, Python, Tcl, Java, JavaScript, R, and Rust.

Source
MongoDB Atlas: What backup options are available?

M0 free tier and Flex tier do not include backups. Dedicated clusters M10 and above include backup services with region and snapshot storage-based pricing.

Source
PostgreSQL: What is ACID compliance in PostgreSQL?

PostgreSQL has been ACID-compliant since 2001, ensuring data integrity through atomicity, consistency, isolation, and durability guarantees for all transactions.

Source
PostgreSQL: Does PostgreSQL support JSON data?

Yes. PostgreSQL supports JSON and JSONB data types for storing and querying JSON documents, along with XML and other document formats.

Source
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