Local-first software is a paradigm where your data lives on your device first and syncs to the cloud second. It provides instant responsiveness, offline support, and data ownership by default.
The Problem Local-First Solves
Traditional web apps require a server round trip for every action. Click save, wait for the server, see the result. If you are offline, nothing works.
Local-first apps write to local storage instantly. Changes sync in the background when connectivity is available. The experience is:
- Instant: No waiting for server responses
- Resilient: Works offline automatically
- Private: Your data stays on your device
- Fast: Reads from local database, zero network latency
Key Technologies
CRDTs (Conflict-free Replicated Data Types)
Data structures that automatically resolve conflicts when multiple devices edit the same document simultaneously. No server arbitration needed.
Sync Engines
- ElectricSQL: Sync PostgreSQL to the client
- PowerSync: Sync any backend to SQLite on the client
- Replicache: Client-side sync framework
- Triplit: Full-stack sync database
- LiveStore: Reactive local-first data store
Storage
- IndexedDB: Browser-native structured storage
- SQLite (via WASM): Full SQL database in the browser
- OPFS: Origin Private File System for fast local storage
Real-World Applications
- Linear: Issue tracker with instant interactions (local-first)
- Figma: Real-time collaborative design (CRDT-based)
- Notion: Moving toward local-first for offline support
- Obsidian: Local-first note-taking
- Excalidraw: Whiteboard with real-time collaboration
Benefits for Businesses
- Better UX: Instant response times regardless of server location
- Reliability: Application works during network outages
- Global performance: No dependency on server proximity
- Reduced server costs: Less compute needed when clients handle their own state
- Data ownership: Users control their data
Challenges
- Complexity: CRDT-based sync is harder to implement than client-server
- Conflict resolution: Edge cases in collaborative editing
- Storage limits: Browser storage quotas (varies by browser)
- Initial sync: Large datasets take time to download initially
- Security: Protecting data on client devices
Our View
Local-first architecture is ideal for collaboration tools, note-taking apps, and productivity software. For content websites and e-commerce, traditional server-rendered architectures remain simpler and more appropriate. We evaluate local-first for projects where offline support or real-time collaboration is a core requirement.