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Developer Tools · head to head

Keycloak vs MongoDB Atlas

Keycloak logo

Keycloak

Developer Tools

Open-source identity and access management server.

From
Free
Free plan
Yes
Full reviewWebsite
MongoDB Atlas logo

MongoDB Atlas

Technology

The multi-cloud developer data platform

From
Free
Free plan
Yes
Full reviewWebsite

The short version

  • Each has a real cost: Keycloak requires self-hosted deployment and operational expertise to install, configure and maintain; MongoDB Atlas m0 free tier limited to learning and exploration only with no backup capability
  • Prices and features above were last checked on 29 August 2026.

Where they differ

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

Attributes where Keycloak and MongoDB Atlas differ
AttributeKeycloakMongoDB Atlas
Pricing modelopen-sourceusage-based
PlatformsSelf-hosted, Docker, Kubernetes, Linux, Windows, APIWeb
CategoryDeveloper ToolsTechnology

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

What people use each for

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

Keycloak

  • Organisations requiring self-hosted identity infrastructure for compliance or data residencynot MongoDB Atlas
  • Companies with existing LDAP/Active Directory systems needing federated authenticationnot MongoDB Atlas
  • Open-source projects and communities requiring free IAM without licensing costsnot MongoDB Atlas
  • Enterprises building custom identity workflows requiring fine-grained authorisationnot MongoDB Atlas
  • Teams with sufficient operational expertise to manage infrastructurenot MongoDB Atlas

MongoDB Atlas

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

Where each one falls short

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

Keycloak

  • Requires self-hosted deployment and operational expertise to install, configure and maintain
  • No managed cloud option provided by Red Hat; organisations must operate infrastructure themselves or use third-party distributions
  • Clustering and high-availability configurations require additional operational knowledge
  • Community support only; commercial support requires third-party vendors or distributions

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

Pricing, plan by plan

Keycloak

Free
  • Open-sourceFree
    • Full platform functionality
    • Self-hosted deployment
    • Community support

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/month
    • 2 GB storage
    • Shared RAM and vCPU
  • M5 Shared$25/month
    • 5 GB storage
    • Shared RAM and vCPU

Which should you pick?

Choose Keycloak if

  • You want to start without paying.
  • You work on Self-hosted, Docker, Kubernetes, Linux, Windows, API.
Keycloak review

Choose MongoDB Atlas if

  • You want to start without paying.
MongoDB Atlas review

Questions people ask

Is Keycloak or MongoDB Atlas better?
Neither clearly leads. Keycloak starts at Free and MongoDB Atlas at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Keycloak or MongoDB Atlas?
Keycloak starts at Free and MongoDB Atlas at Free.
Does Keycloak or MongoDB Atlas run on more platforms?
Keycloak runs on Self-hosted, Docker, Kubernetes, Linux, Windows, API. MongoDB Atlas runs on Web.
Can I use Keycloak for free?
Both have a free tier, so you can try either at no cost before committing.
What is Keycloak best used for?
Keycloak is most often used for organisations requiring self-hosted identity infrastructure for compliance or data residency, companies with existing ldap/active directory systems needing federated authentication, open-source projects and communities requiring free iam without licensing costs, enterprises building custom identity workflows requiring fine-grained authorisation. Of those, organisations requiring self-hosted identity infrastructure for compliance or data residency and companies with existing ldap/active directory systems needing federated authentication are not what MongoDB Atlas is typically brought in for.

Answered from the vendors’ own pages

Keycloak: What protocols does Keycloak support?

Keycloak supports OpenID Connect, OAuth 2.0 and SAML 2.0 protocols for authentication and authorisation.

Source
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
Keycloak: Can Keycloak integrate with existing user directories?

Yes. Keycloak supports user federation with LDAP and Active Directory systems, allowing organisations to leverage existing user directories.

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
Keycloak: Is Keycloak free?

Yes. Keycloak is fully open-source and free to deploy and use. No licensing fees are required.

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
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
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