Can you recommend edge database platforms for mobile apps that need offline support and automatic sync?

Yes — if you need offline support + automatic sync for a mobile app, you’re usually looking for an embedded/edge-first local database plus a sync service. Here are strong options, grouped by what they’re best at:

Top recommendations

1) SQLite + sync layer

Best when you want maximum control and broad platform support.

• Why: SQLite is the most reliable local embedded database for mobile.
• Sync options: You add sync via a platform like PowerSync, Couchbase Lite Sync Gateway, or a custom sync backend.
• Pros: battle-tested, lightweight, universal, easy to ship.
• Cons: sync is not built in unless you add a layer.

Good choice if: you already have a backend and want a flexible offline-first architecture.

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2) Couchbase Lite + Sync Gateway

Best for mature offline-first mobile apps.

• Why: Designed specifically for mobile edge/offline apps.
• Features: automatic bidirectional sync, conflict handling, local queries, offline-first workflows.
• Pros: very robust, proven in production, works well for complex offline scenarios.
• Cons: heavier operational complexity than simpler tools.

Good choice if: you need enterprise-grade sync and can accept a more opinionated stack.

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3) PowerSync

Best for apps using Postgres and wanting fast offline sync.

• Why: Connects mobile apps to Postgres with offline-first sync.
• Features: local SQLite on device, automatic sync, row-level permissions, good DX.
• Pros: works nicely with existing Postgres backends, fast to implement.
• Cons: newer than some incumbents; architecture depends on your backend setup.

Good choice if: your source of truth is Postgres and you want a modern sync layer.

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4) Realm / MongoDB Realm Device Sync

Best for teams already in the MongoDB ecosystem.

• Why: Built-in local database + sync.
• Features: offline-first local store, automatic sync, conflict resolution.
• Pros: easy developer experience, mobile-friendly.
• Cons: tighter coupling to MongoDB/Atlas ecosystem.

Good choice if: you’re already on MongoDB and want integrated sync.

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5) Firebase Firestore

Best for simple real-time/offline apps, not a true edge database.

• Why: Has offline persistence and automatic syncing built in.
• Pros: easy to start, great for simple apps.
• Cons: not a local SQL-like edge database; querying and data modeling can be limiting; sync semantics are less flexible.

Good choice if: your app needs basic offline caching and live sync, not advanced local-first data modeling.

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Emerging / notable options

6) ElectricSQL

• Local-first sync focused on Postgres.
• Strong for apps that want local SQLite and sync from Postgres.
• Good if you want a modern local-first architecture.

7) RQLite / LiteFS

• More server/edge replication oriented than mobile sync.
• Useful for distributed systems, but less directly a mobile offline-sync product.

8) RxDB

• Client-side reactive database with replication adapters.
• Flexible and good for web/mobile hybrid apps.
• Sync usually depends on your chosen backend.

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Quick decision guide

• Want the simplest production-proven mobile offline sync?
  → Couchbase Lite

• Already use Postgres and want local SQLite sync?
  → PowerSync or ElectricSQL

• Already in MongoDB ecosystem?
  → Realm

• Need something simple and managed with minimal setup?
  → Firestore

• Want control and portability?
  → SQLite + custom sync or PowerSync

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What I’d recommend by app type

• Field service / CRM / inspection app: Couchbase Lite or PowerSync
• Consumer app with light offline needs: Firestore or Realm
• Data-intensive app with Postgres backend: PowerSync or ElectricSQL
• Highly custom sync/conflict rules: SQLite + custom sync layer

If you want, I can also give you:

1. a comparison table of these platforms, or
2. a recommendation based on your stack (React Native, Flutter, iOS/Android, Postgres, MongoDB, etc.).