I’m building a cross-industry service platform that lets customers instantly book qualified engineers for IT support, general maintenance and MEP works. The scope covers two user roles only—customers and service engineers—each with its own mobile interface, while a shared backend keeps everything in sync. Core flow • Users sign up and log in exclusively with a phone number OTP flow. • Customers search or filter service categories, enter job details, confirm the request and see the engineer’s live approach on Google Maps once the task is accepted. • Engineers receive real-time job notifications, review details, head to the site and update status points (on the way, arrived, completed), again reflected through live map tracking and whats-up integration nad payment options with review. Technical expectations The mobile front end should run smoothly on both iOS and Android, preferably through a single codebase such as Flutter or React Native, but I’m open to your recommendation. A lightweight, well-documented REST/GraphQL API layer will handle authentication, bookings, geolocation updates (using the Google Maps SDK/Places API) and push notifications. Security, data validation and clean code structure are essential. Deliverables – Customer app build (iOS & Android) – Engineer app build (iOS & Android) – Backend source with API documentation and basic environment files – Google Maps live-tracking integration fully wired to both apps – OTP authentication flow connected to a reliable SMS gateway – Short hand-off guide so I can run the stack locally and deploy to production Acceptance criteria include: OTP verification must succeed ≥95 % of the time on common carriers, map tracking should update within five-second intervals, and all booking status changes must persist after network loss. If this aligns with your expertise, tell me which tech stack you’d use and a ballpark timeline for each milestone so we can move forward quickly.