PowerSync

Sync engine for local-first apps with offline support and real-time data reconciliation.

Overview

PowerSync is a sync engine that bridges backend databases (Postgres, MongoDB, MySQL, SQL Server) with in-app SQLite, enabling automatic data synchronization without complex API management. It consists of a cloud service that handles high-scalability partial data syncing and client SDKs that manage local persistence, consistency, and real-time reactivity.

The platform is designed to eliminate the "network tarpit" of traditional state management by moving data transfer off the critical user interaction path. Developers get instant-responsive apps with offline-first capabilities, real-time updates, and automatic conflict resolution—all while maintaining full control over backend logic.

PowerSync itself is open-source and source-available, supporting popular ORMs and working seamlessly with both relational and document data structures.

Key features

Real-time sync with Sync Streams
Bi-directional automatic partial syncing
JWT-based authentication
Live query reactivity
Conflict resolution
Horizontal scalability
Management dashboard
Monitoring and alerting tools
SOC 2 and HIPAA compliance available

Pros

Eliminates complex API-based state management
Instant offline-first functionality
Real-time data updates across clients
Works with major backend databases
Open-source and self-hostable
Minimal permissions required on backend
Supports popular ORMs
Handles network failures and retries automatically

Cons

Free tier projects deactivate after 1 week of inactivity
Requires understanding of sync architecture concepts
Some advanced features (sharded databases, incremental reprocessing) marked as planned
Learning curve for optimal sync stream design

Use this if

You need offline-first functionality, want to eliminate complex client-side state management, require real-time data sync across multiple clients, or are building with SQLite on the client side.

Skip this if

You don't need offline capabilities, prefer REST/GraphQL APIs for all data transfer, or are not using Postgres, MongoDB, MySQL, or SQL Server as your backend.

Best for

Offline-first mobile and web applicationsReal-time collaborative appsApps requiring instant user responsivenessReducing client-side state management complexityBuilding with SQLite on the clientTeams using Postgres, MongoDB, MySQL, or SQL Server

Alternatives

Realm SyncFirebase Realtime DatabaseSupabase RealtimeWatermelonDBCouchbase Mobile

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