Modern navigation applications provide route information, distance, travel duration, turn-by-turn directions, and location-based services, but most depend strongly on continuous Internet connectivity. This becomes a limitation in rural regions, highways, hilly areas, and emergency situations where network coverage may be unstable or unavailable. This paper presents an Optimal Route Finder, an offline-first hybrid navigation web application designed for Tamil Nadu, India. The proposed system combines live online routing services with a client-side offline routing engine. During online operation, Open Source Routing Machine (OSRM) and Google Routes API are used for live route calculation, while relevant route and location information is cached using browser-based IndexedDB. When connectivity is unavailable, the application automatically switches to an A* pathfinding engine operating on a locally stored road-network graph. The local dataset contains road nodes and edges, geographical places, hospitals, emergency facilities, EV charging stations, weather information, and route-related information covering important road corridors across Tamil Nadu. The architecture also supports offline place search and route-aware searches for hospitals and EV charging stations. By treating Internet connectivity as an enhancement rather than a strict requirement, the proposed system maintains essential navigation functionality during network loss while continuing to exploit live services whenever connectivity is restored.In a feasibility evaluation on five Tamil Nadu route corridors, offline route computation averaged 24.4 ms compared with 423.0 ms for online routing (about 17 times faster), with success rates of 99.7% and 99.8%, respectively.

Offline- first navigation,Road Network Graph,Hybrid Route Planning,Offline-First Navigation,A* path,Intelligent transportation,Emergency routing