David Zequeira Zorrilla

Built and own, end-to-end, two enterprise applications for Android and iOS — a logistics & distribution platform and a fuel dispatch & management platform — both published to the Google Play Store and App Store. Practiced hybrid development daily: built high-performance Flutter features while developing and maintaining core native Android modules in Kotlin with custom MethodChannels/platform channels, bypassing third-party limitations, managing runtime permissions and staying compliant with Google Play permission policies. Implemented OAuth 2.0 / OpenID Connect SSO (flutter_appauth) with the full authorization-code flow, automatic token refresh and secure token persistence (flutter_secure_storage), strengthening user-identity and session security. Restructured the app into a strict Layered / Hexagonal architecture (Presentation–Domain–Data) with Riverpod, decoupling business logic from framework dependencies and enabling isolated domain use-case testing and independent evolution of backend API contracts. Authored custom Dart libraries that cut UI rendering times by 25%, and implemented offline-first synchronization reaching 99.9% sync reliability with an 80% reduction in data transfer through payload, caching and conflict-resolution optimizations. Owned the full release lifecycle and post-release monitoring: automated Play Store and TestFlight deployments with Fastlane + GitHub Actions (39 production builds across multiple client apps) and led the end-to-end architectural evolution and legacy-codebase migration. Integrated device hardware where required — barcode/QR scanning (Scandit SDK), Bluetooth/WiFi peripherals, digital-signature capture and background services on industrial Android devices.

Led a mobile team and mentored 2 developers on Flutter, Firebase and Google Cloud, raising team capability and delivery quality. Introduced and scaled an AI-assisted engineering practice across the team — adopting the Claude ecosystem (agents, skills, hooks) together with spec-driven and agentic development workflows — then standardized and rolled it out to other teams company-wide, improving delivery speed and consistency. Delivered three cross-platform apps for Android, iOS and Web from a single Flutter codebase within a 5-month timeframe, significantly accelerating time-to-market.

Managed full iOS releases in Xcode / App Store Connect — provisioning profiles, certificates, TestFlight distribution and final submission — and configured Fastlane Match for team-wide code signing; built CI/CD pipelines (build signing, version bumping, automated deployments) for iOS and Android.

Integrated Firebase Crashlytics from inception across three apps; resolved a Socket.IO reconnection race condition and device-specific crashes, raising crash-free sessions from 94% to >99%, with automated Slack alerts on crash-rate spikes. Implemented Firebase Analytics across all apps to track feature adoption and engagement, informing product-roadmap and UI/UX decisions; translated customer requirements into actionable Flutter features with design, QA and backend teams.

Large-scale consumer mobility platform (100k+ users) & smart-home app

Contributed to a large-scale consumer mobility app with 100,000+ users (published on Google Play), implementing BLoC/Cubit state management that cut UI latency by ~50–100 ms and improved testability, maintainability and performance at scale.

Integrated payment gateways and multiple third-party SDKs (Firebase services, Scandit QR scanning, analytics, peripherals), handling sensitive transaction flows and secure data exchange between mobile clients and backend services.

Integrated REST, Socket.IO, GraphQL (Apollo, graphql-flutter) and Mapbox, reducing API response times by 15% and improving data-flow reliability; applied Clean Architecture to bridge Flutter and native code. Achieved 90% test coverage with unit and widget tests (Mockito, bloc_test), reducing bugs ~10–15%; established CI/CD with GitHub Actions, containerized services with Docker and used Azure cloud services. As full-stack engineer, built and maintained the Coqon Flutter app — stabilizing the Provider layer with defensive parsing to cut crash rates 10–15% — and designed optimized data contracts in PHP (Yii) across PostgreSQL, MongoDB and MySQL, gaining end-to-end visibility across the mobile and backend stack.