RxDB
Reactive client-side database for JavaScript applications. RxDB wraps various storage backends (IndexedDB, SQLite, in-memory) with RxJS observables, enabling reactive queries that automatically emit when data changes. Supports real-time replication with CouchDB/PouchDB, GraphQL, and WebSocket sync protocols. Works in browsers, Node.js, React Native, and Electron. Strong focus on local-first apps with offline capability and eventual sync.
Score Breakdown
⚙ Agent Friendliness
🔒 Security
Apache 2.0 open source core. Local-only storage — security is client environment dependent. Encryption plugin available for at-rest security. Sync security is transport-level (HTTPS). No auth built-in.
⚡ Reliability
Best When
You're building offline-first JavaScript apps with reactive UI updates, need flexible storage backends, and want built-in sync with various server protocols.
Avoid When
Your app is server-side, you don't need reactive queries, or you prefer SQL — use PouchDB for simpler offline sync or SQLite directly.
Use Cases
- • Build offline-first web applications with IndexedDB storage and RxDB's reactive query layer that auto-updates the UI on data changes
- • Implement real-time local-first sync with CouchDB or custom GraphQL backends using RxDB's built-in replication protocols
- • Create progressive web apps (PWA) that work fully offline and sync changes when connectivity is restored using RxDB's conflict handling
- • Build agent local caches with reactive observation — agent components automatically re-evaluate when underlying data changes in RxDB
- • Use RxDB's query change detection to build reactive agent pipelines that trigger on specific data conditions
Not For
- • Server-side applications at scale — RxDB is client-side focused; use PostgreSQL or MongoDB for server-side storage
- • Simple CRUD applications without reactive requirements — RxDB's complexity is unnecessary for basic local storage
- • Applications requiring complex SQL joins — RxDB's query language is JSON-based (like MongoDB), not SQL
Interface
Authentication
Local database library — no auth. Auth is handled by the replication server endpoint. RxDB's replication plugins accept custom headers and auth tokens for sync server authentication.
Pricing
Core RxDB is Apache 2.0 free. RxDB Premium adds high-performance storage plugins (SQLite, FoundationDB) and advanced replication features. Most use cases are covered by the free tier.
Agent Metadata
Known Gotchas
- ⚠ RxDB requires schema versioning for all collections — schema changes require a migration function; no automatic migration; version mismatch throws an error on collection creation
- ⚠ Reactive queries return RxJS Observables, not Promises — agents using async/await must call .exec() for one-time queries instead of subscribing to observable
- ⚠ RxDB's in-memory storage is not persistent across page reloads — production apps must use IndexedDB (browser) or SQLite (Node.js/native) storage plugin
- ⚠ Document encryption requires the RxDB encryption plugin — data is not encrypted at rest by default; sensitive agent data requires explicit encryption setup
- ⚠ The replication protocol requires specific REST API format from the sync server (pull/push endpoints with specific JSON structure) — existing servers need an adapter layer
- ⚠ RxDB's query planner is limited compared to SQL databases — complex filtered queries on large collections may require manual index definition to avoid full collection scans
Alternatives
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Scores are editorial opinions as of 2026-03-07.