A POS system built for small and medium businesses in Sri Lanka, designed to work reliably even with unreliable internet connectivity.
Architecture
The system used a local-first architecture: each installation ran a local server with a web-based POS interface. Transactions were stored locally and synced to a central server when connectivity was available.
Key technical decisions:
- Offline-first — all critical operations worked without internet
- Queue-based sync — transactions queued locally
- Credit management — built-in support for credit customers
Challenges
The offline sync mechanism was the hardest technical problem. We implemented a last-write-wins strategy with manual reconciliation for edge cases.