Денис

Denys Filonenko
Senior Flutter Engineer · Kyiv, Ukraine
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Summary
Flutter engineer with 6+ years in software development, including 5 years building production
Flutter apps for Android and iOS. Experienced in owning mobile apps end to end as a sole
developer, from architecture to store releases.
Strong at decomposing complex legacy code, designing client architecture, integrating backends,
profiling performance and tracking down hard issues to their root cause, from native build
tooling conflicts to device-specific bugs.
I enjoy taking ownership: making technical decisions, proposing and driving improvements, and
seeing them through to production. I work closely with backend, QA and product, and
communicate trade-offs openly.

Experience
CASAFARI — Mobile Application Developer
Jan 2024 – Nov 2026 · Remote (Lisbon, Portugal)
CASAFARI AI is a real-estate intelligence app that aggregates property data from all major portals
in many European countries and the UAE into one platform (App Store, Google Play).
● Owned an app with 20,000+ downloads end to end as the sole Flutter developer, including
App Store and Google Play releases through CI/CD (Jenkins, Fastlane, GitHub Actions).
● Re-architected the app from MobX to Riverpod with Clean Architecture, MVVM and
feature-based modules; decomposed large legacy controllers (the largest over 2,000 lines)
into focused, testable state modules.
● Built map-based property search on Google Maps with clustering, draw-to-search and
viewport-driven filtering behind a library-agnostic map abstraction.
● Delivered features and integrations: OAuth sign-in, saved-search push alerts, deep links,
valuation reports, QR login; REST API (Dio), Firebase, PostHog, reCAPTCHA.
● Improved rendering performance on Android and iOS: up to 20% faster frame times and up
to 70% less jank, verified by before/after profiling.

Qooco — Flutter Developer
Nov 2021 – Jan 2024
Qooco Talk is an English and Chinese learning app; 5,000+ downloads on Google Play.
● Migrated modules of the legacy native app to Flutter.
● Built new features and interactive learning lessons using BLoC and Cubit.
● Developed interactive mini-games with the Flame game engine and Spine animations.
● Took part in app architecture and business logic design.

Taxi UA — Cross-Platform App Developer
Nov 2020 – Nov 2021
Taxi UA is an app for taxi drivers in Ukraine with direct fuel discounts at partner filling stations
and related driver services.
● Built and shipped an app that reached 100,000+ downloads as the sole developer, from
development to Google Play release; built with Vue.js and Apache Cordova.
● Implemented custom native Cordova modules and Firebase integration.
● Worked with IT teams of filling-station chains and other partners on service integrations.

Earlier experience
● SoftLogic Taxi — Frontend Developer, Jun 2020 – Nov 2020: web modules integrated into
taxi service mobile apps.

Skills
● Core: Dart, Flutter (Android, iOS)
● Architecture: Clean Architecture, SOLID, MVVM, feature-based modularization,
dependency injection
● State management: Riverpod, BLoC / Cubit, Provider, MobX
● Networking: REST API, Dio, http, OAuth 2.0, JWT, cookie and session-based auth, error
handling
● Maps: Google Maps, GPS geolocation, GeoJSON, clustering, drawing on the map
● Storage & caching: Hive, sqflite / Drift, shared_preferences, flutter_secure_storage
● Services & integrations: Firebase, push notifications, deep links, PostHog, reCAPTCHA
● CI/CD: Jenkins, Fastlane, GitHub Actions, Git, App Store and Google Play releases
● Testing: unit, widget and integration tests (flutter_test, mocktail), testable architecture
through dependency injection
● Process & tools: Agile, Git flow, Claude Code (AI-assisted development)
● Web: JavaScript, TypeScript, Vue.js, React, Redux, HTML/CSS
● Languages: English (Upper-Intermediate, B2), Ukrainian (native)

Education
Master's in Finance; courses: Web Development (IT Step, 2019–2020), React (SoftServe,
2020–2021).