Offline-First Field Audit Platform (Web + Mobile)

Field auditors work in parks and public spaces where connectivity is unreliable. Paper forms meant re-keying everything later, and any app that assumed a live connection would lose an auditor's work the moment they walked out of range.

Two products on one typed backend. A React Native and Expo app that runs a complete audit offline, using Legend State and MMKV for local persistence with background sync when the connection returns. And a Next.js dashboard where coordinators manage sites, review submissions, and export results.

Behind both sits a FastAPI service on PostgreSQL with SQLAlchemy: role-based access control, draft save and resume, normalized scoring pipelines, and client-side CSV, XLSX, and PDF export.

Offline is the default path, not a fallback. Every write lands in local state first and syncs after, so the app behaves the same in a dead zone as it does on wifi.

Draft-save was hardened against duplicate-key failures that only surfaced during multi-round field testing. Real auditors found edge cases no test suite had.

Scoring is normalized server-side, so a partially completed audit still produces a comparable result instead of an error.

Accessibility and i18n were configured from the start for a diverse field-worker population, not retrofitted later.

I instrumented both products with PostHog for funnels and product analytics, Sentry for error and performance monitoring, and Microsoft Clarity for session replay. That turned real field usage into signal: which steps auditors abandoned, which errors were failing silently, and where the interface slowed people down.