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MongoDB vs Postgres

MongoDB logo

MongoDB

Technology

The developer data platform

From
Free
Rated
-
Full reviewWebsite
Postgres logo

Postgres

Technology

The world's most advanced open source database

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: MongoDB 16 MB maximum document size limits large single objects; Postgres each major version is supported for only 5 years after its initial release, after which it is end-of-life
  • They diverge on capability: MongoDB covers Document model, Postgres covers ACID compliance.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which MongoDB and Postgres actually diverge.

Attributes where MongoDB and Postgres differ
AttributeMongoDBPostgres
Pricing modelUnknownopen-source
PlatformsCloud (Atlas), Self-hosted, Multi-cloud (AWS, Google Cloud, Azure)Linux, Windows, Macos, Docker
Founded20071996

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

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
  • Time series data
  • Geospatial queries
  • Aggregation framework
  • C#

Only in Postgres

  • ACID compliance
  • Complex queries
  • Foreign keys
  • Triggers
  • Views
  • Stored procedures
  • JSON/JSONB support
  • Rust

Both cover

  • Full-text search
  • Node.js
  • Python
  • Java
  • .NET
  • Go
  • Ruby
  • PHP
  • Encryption
  • Authentication

What people use each for

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

MongoDB

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

Postgres

  • Running a general purpose relational database for applicationsnot MongoDB
  • Self-hosting an open source SQL database with no licence feenot MongoDB
  • Workloads needing extensions, JSON and full text search in one enginenot 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

Postgres

  • Each major version is supported for only 5 years after its initial release, after which it is end-of-life
  • Major version upgrades break on-disk compatibility and require a full dump and reload or the pg_upgrade tool
  • New major versions ship about once a year, so staying supported means a disruptive upgrade cycle
  • Minor releases contain only frequently-encountered bug fixes, low-risk fixes, security issues and data corruption fixes, so feature gaps are not addressed within a major version
  • There is no vendor SLA; commercial support must be bought separately from third party professional services listed by the project

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

Postgres

Free
  • Community EditionFree
    • Full database features
    • No limitations
    • Community support

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.
MongoDB review

Choose Postgres if

  • You need acid compliance.
  • You want to start without paying.
  • You work on Linux, Windows, Macos, Docker.
  • You also want complex queries.
Postgres review

Questions people ask

Is MongoDB or Postgres better?
Neither clearly leads. MongoDB starts at Free and Postgres at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, MongoDB or Postgres?
MongoDB starts at Free and Postgres at Free.
Does MongoDB or Postgres run on more platforms?
MongoDB runs on Cloud (Atlas), Self-hosted, Multi-cloud (AWS, Google Cloud, Azure). Postgres runs on Linux, Windows, Macos, Docker.
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 Postgres is typically brought in for.
What can MongoDB do that Postgres cannot?
MongoDB covers Document model, Distributed architecture, ACID transactions, Real-time analytics. Postgres covers ACID compliance, Complex queries, Foreign keys, Triggers. Both handle Full-text search, Node.js, Python, Java.

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.

Source
Postgres: How much does PostgreSQL cost to use?

PostgreSQL is completely free to download, install, and use. No licensing fees, subscription costs, or per-seat charges apply. The database is open source under the PostgreSQL License. Source: https://www.postgresql.org

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
Postgres: Are there commercial PostgreSQL support options available?

Official PostgreSQL (the project) is free. Commercial PostgreSQL services such as hosting, professional support, training, and managed database services are offered by third-party vendors, not the PostgreSQL project itself. Source: https://www.postgresql.org

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
Postgres: Do I need a license to use PostgreSQL commercially?

No. PostgreSQL is open source under the PostgreSQL License, which permits free commercial use without royalties, licensing fees, or support obligations. Source: https://www.postgresql.org

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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