Heavy Machinery mobile-first

Problem

Field workers at US heavy machinery dealerships need to browse, configure, and order equipment from mobile devices while on-site at job sites. They don't carry laptops, connectivity at construction sites is unreliable, and the existing web app was too slow and clunky on a phone screen.

Sales reps were losing deals because they couldn't show real-time pricing and configuration options to buyers in the field. The web app's desktop-first design meant touch targets were too small, navigation required too many taps, and page loads took 8+ seconds on LTE.

Solution

We built a native mobile app using React Native + Expo, designed from the ground up for field use. The architecture decision that had the biggest impact was building the cart-state contract first — before any UI work. Every screen became a consumer of the same state machine, which meant the offline mode worked on day one.

The app uses Expo for the development workflow (fast reloads, EAS builds) and OTA (Over-The-Air) updates for quick iteration between App Store review cycles. The App Store review process was a learning curve — Apple flagged the initial submission for in-app purchase configuration, which required a 2-week correction cycle before approval.

export type CartState = {
  items: CartItem[];
  version: number;
  synced: boolean;
};

The backend gateway bridges the mobile app to the existing Odoo ERP. We built a Fastify + Bun service that translates mobile API calls into Odoo XML-RPC requests, with Zod validation boundaries at every layer to prevent bad data from reaching the ERP.

Impact

98%cart operations available offline before network sync

4.8★App Store rating after first release

Field workers can now configure and quote heavy machinery orders on-site, with cart operations fully available offline and automatic sync when connectivity returns. The App Store rating of 4.8 stars reflects the reliability of the offline-first approach — buyers trust the app to work even at remote job sites with no signal.

Stack

• Mobile: React Native + Expo (OTA updates, EAS builds, App Store review)
• Gateway: Fastify + Bun (XML-RPC to Odoo, Zod validation boundaries)
• Cart-state: Offline-first contract, version-based sync