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Technology · head to head

MongoDB vs Redis

MongoDB logo

MongoDB

Technology

The developer data platform

From
Free
Rated
-
Full reviewWebsite
Redis logo

Redis

Technology

The real-time data platform

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: MongoDB 16 MB maximum document size limits large single objects; Redis licensing changed from BSD to AGPL in 2025, impacting open-source usage
  • They diverge on capability: MongoDB covers Document model, Redis covers In-memory data store.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which MongoDB and Redis actually diverge.

Attributes where MongoDB and Redis differ
AttributeMongoDBRedis
PlatformsCloud (Atlas), Self-hosted, Multi-cloud (AWS, Google Cloud, Azure)Linux, macOS, Windows
Founded20072009

Identical on both: starting price (Free), pricing model (Unknown), 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
  • Full-text search
  • Time series data
  • Geospatial queries
  • Aggregation framework

Only in Redis

  • In-memory data store
  • Data structures
  • Pub/Sub messaging
  • Lua scripting
  • Transactions
  • Persistence options
  • Replication
  • Clustering

Both cover

  • Node.js
  • Python
  • Java
  • C#
  • .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 Redis
  • Content managementnot Redis
  • Real-time analytics
  • IoT applicationsnot Redis
  • Gaming backendsnot Redis

Redis

  • Cachingnot MongoDB
  • Session managementnot MongoDB
  • Real-time analytics
  • Message queuingnot MongoDB
  • Leaderboardsnot MongoDB

Both are used for real-time analytics, on those jobs the choice comes down to price and fit rather than capability.

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

Redis

  • Licensing changed from BSD to AGPL in 2025, impacting open-source usage
  • All data must fit in memory, limiting scalability to available RAM
  • No built-in support for multi-tenancy
  • Limited transaction support compared to traditional databases

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

Redis

Free

No published plan breakdown. See the Redis review.

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 Redis if

  • You need in-memory data store.
  • You want to start without paying.
  • You work on Linux, macOS, Windows.
  • You also want data structures.
Redis review

Questions people ask

Is MongoDB or Redis better?
Neither clearly leads. MongoDB starts at Free and Redis at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, MongoDB or Redis?
MongoDB starts at Free and Redis at Free.
Does MongoDB or Redis run on more platforms?
MongoDB runs on Cloud (Atlas), Self-hosted, Multi-cloud (AWS, Google Cloud, Azure). Redis runs on Linux, macOS, Windows.
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 Redis is typically brought in for.
What can MongoDB do that Redis cannot?
MongoDB covers Document model, Distributed architecture, ACID transactions, Real-time analytics. Redis covers In-memory data store, Data structures, Pub/Sub messaging, Lua scripting. Both handle Node.js, Python, Java, C#.

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
Redis: Is Redis open source?

Redis was open source under the BSD license since its inception in 2009 and has remained open source. However, in 2024-2025, Redis Labs changed licensing to source-available and AGPL, prompting the creation of Valkey, a BSD-licensed open-source fork.

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
Redis: What is Redis used for?

Redis is an in-memory data structure store used primarily as a cache, database, and message broker. It provides high-speed data access for real-time applications, sessions, leaderboards, real-time analytics, and other use cases requiring fast data retrieval.

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
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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