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Firebase Realtime Database vs Keycloak

Firebase Realtime Database logo

Firebase Realtime Database

Databases

Store and sync data in real-time across all clients

From
Free
Free plan
Yes
Visit Firebase Realtime DatabaseFull review
Keycloak logo

Keycloak

Developer Tools

Open-source identity and access management server.

From
Free
Free plan
Yes
Visit KeycloakFull review

The short version

  • Firebase Realtime Database is a cloud-hosted NoSQL database; Keycloak is an open-source IAM platform supporting OpenID Connect, OAuth 2.
  • Keycloak is free; Firebase Realtime Database starts at $5/mo.
  • Where Firebase Realtime Database falls short: the no-cost Spark plan caps storage at 1 GB, downloads at 10 GB per month and simultaneous connections at 100.
  • Where Keycloak falls short: requires self-hosted deployment and operational expertise to install, configure and maintain.
  • Prices and features on this page were last checked on 13 November 2026.

Where they differ

Only the attributes on which Firebase Realtime Database and Keycloak actually diverge.

Attributes where Firebase Realtime Database and Keycloak differ
AttributeFirebase Realtime DatabaseKeycloak
Pricing modelFreemiumOpen-source
PlatformsWeb, iOS, AndroidSelf-hosted, Linux, Windows, API
CategoryDatabasesDeveloper Tools

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

Not yet recorded: founded for Keycloak.

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 Firebase Realtime Database

  • Real-time Sync
  • Offline Support
  • JSON Storage
  • Security Rules
  • Data Validation
  • Multi-platform SDKs
  • Scalable
  • Firebase Auth

Only in Keycloak

Nothing recorded that Firebase Realtime Database does not also cover.

What people use each for

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

Firebase Realtime Database

  • Syncing JSON application state between clients in real timenot Keycloak
  • Backing mobile and web apps with offline capable data storagenot Keycloak
  • Prototyping realtime features such as presence and chatnot Keycloak

Keycloak

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

Where each one falls short

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

Firebase Realtime Database

  • The no-cost Spark plan caps storage at 1 GB, downloads at 10 GB per month and simultaneous connections at 100
  • The Spark plan does not support multiple databases in a project
  • Even on the paid Blaze plan simultaneous connections are capped at 200,000 per database
  • Billing is by data transferred out at $1 per GB plus $5 per GB stored, so chatty clients cost more than the data volume suggests

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

Pricing, plan by plan

Firebase Realtime Database

Free
  • SparkFree
    • 1 GB data storage included
    • 10 GB per month data downloads included
    • No charges for usage within limits
  • Blaze$5
    • Maintains Spark free allowances
    • Pay-as-you-go for usage exceeding limits
    • Billing applies to data stored and outbound network traffic

Keycloak

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

Which should you pick?

Choose Firebase Realtime Database if

  • You need real-time sync.
  • You want to start without paying.
  • You work on Web, iOS, Android.
  • You also want offline support.
Firebase Realtime Database review

Choose Keycloak if

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

Questions people ask

Is Firebase Realtime Database or Keycloak better?
Neither clearly leads. Firebase Realtime Database starts at Free and Keycloak at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Firebase Realtime Database or Keycloak?
Firebase Realtime Database starts at Free and Keycloak at Free.
Does Firebase Realtime Database or Keycloak run on more platforms?
Firebase Realtime Database runs on Web, iOS, Android. Keycloak runs on Self-hosted, Linux, Windows, API.
Can I use Firebase Realtime Database for free?
Both have a free tier, so you can try either at no cost before committing.
What is Firebase Realtime Database best used for?
Firebase Realtime Database is most often used for syncing json application state between clients in real time, backing mobile and web apps with offline capable data storage, prototyping realtime features such as presence and chat. Of those, syncing json application state between clients in real time and backing mobile and web apps with offline capable data storage are not what Keycloak is typically brought in for.
What can Firebase Realtime Database do that Keycloak cannot?
Firebase Realtime Database covers Real-time Sync, Offline Support, JSON Storage, Security Rules.

Answered from the vendors’ own pages

Firebase Realtime Database: How much does Firebase Realtime Database cost?

Firebase Realtime Database offers a free Spark plan (1 GB storage, 10 GB/month downloads) and a pay-as-you-go Blaze plan. On Blaze, storage costs $5 per GB per month, evaluated daily, with no monthly minimum charges.

Source
Keycloak: What protocols does Keycloak support?

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

Source
Firebase Realtime Database: What is included in Firebase Realtime Database free tier?

The Spark plan includes 1 GB of data storage and 10 GB per month of data downloads at no cost. Usage within these limits incurs no charges, making it suitable for small projects and testing.

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
Firebase Realtime Database: Does Firebase Realtime Database charge for denied or rejected operations?

Yes. Firebase charges for all traffic to and from the database on the Blaze plan, including operations denied by security rules, outbound network traffic at the session layer, and connection and encryption overhead from all operations.

Source
Keycloak: Is Keycloak free?

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

Source
Firebase Realtime Database: Can I set a spending limit on Firebase Realtime Database?

Firebase offers budget alerts but does not cap spending automatically. Users must monitor their usage dashboard in the Firebase console to track connections, storage, downloads, and load metrics; a calculator is available for cost estimation.

Source
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