Building Offline-First Mobile Apps for Indian Retail

When we started building CoreAxis ePOS for retail stores in smaller Indian cities, we quickly learned that "always connected" is not a valid assumption. ## The Reality of Connectivity A typical retail store in a Tier 2 city experiences 3-5 connectivity drops per day, network switches, and 15-30 minute outages. For a billing application, this is not an edge case. ## Our Approach: Offline-First **Local-first data storage**: All product catalogs, customer records, and pricing rules sync to the device's SQLite database. The app generates bills and calculates GST without server contact. **Transaction queue**: Every sale and payment is recorded locally with a timestamp. When connectivity returns, the queue syncs chronologically. **Conflict resolution**: Last-write-wins for customer records. Financial transactions are always appended, never deduplicated. ## Key Lessons 1. Test with actual network conditions, not just airplane mode 2. Never block the UI for sync 3. Print receipts from local data, not server responses 4. Make sync recovery fully automatic