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Head-to-head · Mobile Databases

Firebase Realtime Database vs Realm

  • Updated Oct 2026
  • Both researched from official sources
  • 2 checks side by side
Higher score Firebase Realtime Database #5 in Mobile Databases 8.8/10 Free plan Free plan✓ 1 of 1 features Visit Firebase
Realm #8 in Mobile Databases 8.3/10 Open source ✓ 0 of 1 features Explore Realm

Firebase Realtime Database leads on 0 checks, Realm on 0, and 2 are even. Who comes out ahead on the 2 yes/no, price and count checks where we have data for both products. The editor score weighs everything else too.

Our verdict

  • Highest scoreFirebase Realtime Database · 8.8/10
  • Free planonly Firebase Realtime Database
  • Most featuresFirebase Realtime Database · 1 of 1

Firebase Realtime Database scores higher on our rubric for mobile databases: 8.8 against 8.3 out of 10; our editors rank them #5 and #8.

Firebase Realtime Database is the better fit for real-time Firebase mobile applications. Realm is the better fit for legacy object-oriented mobile apps with cloud sync.

  • Firebase Realtime Database fits best

    Real-time Firebase mobile applications

  • Realm fits best

    Legacy object-oriented mobile apps with cloud sync

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Side by side

Feature Firebase Realtime Database 8.8/10 Visit ↗ Realm 8.3/10 Visit ↗
At a glance
Editor score 8.8 8.3
Ranking #5 in Mobile Databases #8 in Mobile Databases
Best for Real-time Firebase mobile applications Legacy object-oriented mobile apps with cloud sync
Pricing model Free plan + paid Free
Starting price — Open source
Free plan ✓ (best) Not checked yet
Free trial — —
Deployment Cloud Self-hosted, Mobile, Desktop
Platforms Web, iOS, Android iOS, Android, Windows, macOS, Linux
Support Email, Tickets, Community, Docs Community, Docs
Integrations 2 integrations 1 integrations
Features Firebase Realtime Database 1/1 · Realm 0/1
Offline mode ✓ (best) Not checked yet
Specs
Data synchronization Bidirectional Not checked yet
Mobile platforms iOS and Android iOS, Android, Xamarin
Conflict resolution Automatic Not checked yet
SDK languages Apple platforms, Android, Flutter, JavaScript, Unity, C++ Java, Objective-C, JavaScript, Swift, Xamarin
Monthly sync limit Not checked yet Not checked yet
Our review
Pros
  • Real-time bidirectional JSON synchronization across connected clients
  • Offline caching, queued writes and automatic conflict merging
  • SDKs, REST access, Security Rules and Cloud Functions integration
  • Local persistence with reactive, object-oriented data access
  • Device-to-cloud synchronization with MongoDB Atlas integration
  • SDK coverage across iOS, Android, Xamarin and multiple languages
Cons
  • Spark limits usage to 1 GB stored data and 100 simultaneous connections
  • Blaze uses usage-based billing rather than a fixed subscription
  • Web offline persistence does not continue beyond the session
  • Atlas Device Sync and Atlas Device SDKs reached end-of-life
  • Not suitable for new projects requiring ongoing platform support
  • Realm branding and documentation now point to legacy technology
Our verdict

Firebase Realtime Database is a cloud-hosted NoSQL database for mobile and web applications that stores data as JSON and synchronizes updates across connected clients in real time. It is designed for developers building Firebase…

Read the review →

Realm was an open-source mobile database and synchronization technology for reactive applications. It provided local mobile data persistence, object-oriented database access, reactive application data access, and device-to-cloud…

Read the review →
  1. Firebase Realtime DatabaseMobile Databases 8.8Free plan
  2. RealmMobile Databases 8.3Open source

Strengths and trade-offs

  • Firebase Realtime Database — where it wins

    • Real-time bidirectional JSON synchronization across connected clients
    • Offline caching, queued writes and automatic conflict merging
    • SDKs, REST access, Security Rules and Cloud Functions integration

    Where it doesn't

    • Spark limits usage to 1 GB stored data and 100 simultaneous connections
    • Blaze uses usage-based billing rather than a fixed subscription
    • Web offline persistence does not continue beyond the session

  • Realm — where it wins

    • Local persistence with reactive, object-oriented data access
    • Device-to-cloud synchronization with MongoDB Atlas integration
    • SDK coverage across iOS, Android, Xamarin and multiple languages

    Where it doesn't

    • Atlas Device Sync and Atlas Device SDKs reached end-of-life
    • Not suitable for new projects requiring ongoing platform support
    • Realm branding and documentation now point to legacy technology
  • Firebase Realtime Database8.8/10 · Free plan

    A strong fit for Firebase apps that need real-time sync and offline mobile access.

    Visit FirebaseFull verdict →
  • Realm8.3/10 · Open source

    A capable object-oriented mobile database now discontinued after Atlas Device SDK end-of-life.

    Explore RealmFull verdict →

More comparisons

All mobile databases comparisons → · Full ranking →

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Last updated · How we research and update