Martin Berger

About

Dedicated engineer with a decade and more of experience in the tech industry, specialized in mobile application development with experience in game development and embedded programming. Member or lead of teams on many iOS and several Android applications. Strives for complete robust solutions.

Work

• Full-Stack Mobile Developer (Contractor)

  UK Express · UK

  2024 – 2026

  Led end-to-end development of a Flutter mobile platform for a UK-based logistics company, working across mobile, .NET backend, and Azure DevOps. Used Claude and Cursor as AI tools throughout development to accelerate architecture decisions, code generation, and problem solving.

  • Built the complete Flutter application from scratch using Riverpod and Clean Architecture (Presentation / Domain / Data layers)
  • Designed and implemented full driver onboarding flow: work preferences, vehicle info, entity type selection, and business details
  • Developed real-time driver tracking with foreground services, persistent notifications, and GPS location monitoring
  • Implemented OTP-based phone number authentication, replacing traditional username/password login
  • Built quote submission and management system allowing subcontractors to bid on delivery loads
  • Integrated Firebase Remote Config for dynamic feature flags and app configuration
  • Implemented connectivity monitoring with live network status indicators
  • Contributed to .NET backend: full feature development including delivery management endpoints and business logic
  • Managed Azure DevOps pipelines for multi-environment CI/CD and used Azure Storage Explorer for blob and config management
  • Built custom UI components following Material Design guidelines: buttons, forms, navigation patterns
  • Created comprehensive logging and tracing system for debugging and runtime monitoring
  • Collaborated closely with backend developer on API design and data synchronization

  Tech: Flutter, Riverpod, Clean Architecture, Firebase Remote Config, .NET, Azure DevOps, Azure Storage, Material Design, GPS / foreground services, OTP auth

• Flutter Developer (Contractor)

  Concord Health · USA

  2023 – 2024

  Developed features for a US healthcare app from initial architecture setup through to production delivery.

  • Set up initial architecture: GraphQL network client, Dio REST client, getIt, go_router, Provider, Firebase
  • Built custom graphic components including animated linear and circular rulers using CustomPainter
  • Implemented Propensity Score Matching onboarding flow and in-app Chat feature
  • Built chat feature using Sendbird SDK and DashChat2 UI library with unread badge on bottom navigation bar
  • Integrated OneSignal push notifications
  • Researched and evaluated chat solutions across pricing and technical fit; presented recommendation to client
  • Built user registration flow using Auth0 and InAppWebView
  • Configured and maintained CodeMagic CI/CD pipeline
  • Added Widgebook for component-level UI testing
  • Onboarded new developers to the project; presented app progress to clients on weekly/biweekly schedule

  Tech: Flutter, GraphQL, Dio, getIt, go_router, Provider, Firebase, CustomPainter, Sendbird, DashChat2, OneSignal, Auth0, InAppWebView, CodeMagic, Widgebook

• Lead Flutter Developer (Contractor)

  Seclo · Netherlands

  2022 – 2023

  Led a team of 2–4 Flutter developers (8 total) building a second-hand marketplace app for the Dutch market.

  • Established and enforced MVVM architecture across the codebase; conducted rigorous code reviews to maintain quality
  • Built custom payment system from scratch using MangoPay and Amplify AppSync, including payment state machines
  • Implemented Know Your Client (KYC) verification for both natural and business users
  • Integrated full auth flows via Amplify.Auth with social logins (Google, Facebook, Apple) through Amazon Cognito
  • Integrated camera for in-app video and photo recording for product and story features
  • Delivered key screens: Home with paging, 7-screen checkout flow with web view, shopping cart, login/registration
  • Set up and managed CodeMagic CI/CD pipeline; handled Flutter version upgrades and library compatibility
  • Used Flutter Amplify as the sole API layer, eliminating need for additional packages like Dio
  • Maintained continuous communication with clients and proposed solutions proactively
  • App Store: https://apps.apple.com/app/seclo/id1637078381 · Play Store: https://play.google.com/store/apps/details?id=com.secloapp.secloapp

  Tech: Flutter, MVVM, getIt, MangoPay, Amplify AppSync, Amplify.Auth, Amazon Cognito, CodeMagic

• Flutter Developer (Contractor)

  Padrino · Food Delivery App

  2022 – 2022

  Food delivery mobile app.

  • Contributed to app architecture; researched state management options and recommended custom Store-based approach over Riverpod for the project's needs
  • Implemented Settings, Profile, and Category screens with custom UI components
  • Built reusable custom buttons and avatar widgets
  • Delivered features using Bloc architecture with clean separation of concerns
  • App Store: https://apps.apple.com/app/padrino-delivery/id1659769843 · Play Store: https://play.google.com/store/apps/details?id=com.padrinodelivery.consumerapp

  Tech: Flutter, Bloc, custom Store architecture

• Senior iOS Engineer (Contractor)

  Starbucks EMEA · EMEA

  2022 – 2022 (6 months)

  Multi-market iOS app with per-country flavors and Fastlane distribution.

  • Fixed WorldPay/3DS payment flows by refactoring Loadable-based API handling for card reload and payment methods
  • Integrated feature branches across legacy ObjC and new Shiny Swift modules during a two-week release window
  • Built market-specific home dashboard widgets with per-country UI injection and custom rewards progress components
  • Golden Test suite (FBSnapshotTestCase, varyParameters, LTR/RTL baselines) for visual regression across core screens
  • Migrated ObjC features to Swift (MVVM + Flow + Loadable), bridged via market-specific class injection
  • Mentored junior developers
  • App Store: https://apps.apple.com/us/app/starbucks/id331177714

  Tech: iOS, Swift, Objective-C, MVVM, Flow, Loadable, Fastlane, FBSnapshotTestCase, WorldPay / 3DS, multi-market / white-label builds

• iOS Developer (Contractor)

  Cozily · Italy

  2021 – 2021

  HealthTech, Italy.

  • Added end-to-end voice messaging to a Twilio-based chat system: audio capture, media upload/download, local cache persistence, and in-thread playback controls
  • Re-architected the Conversations loading pipeline by serializing ~300 async fetches through NSOperationQueue, cutting screen load time from ~10 minutes to a few seconds
  • Improved chat reliability by fixing memory/lifecycle issues and enforcing deterministic channel/message sorting, reducing UI inconsistency and stale-state bugs
  • App Store: https://apps.apple.com/us/app/cozily-terapia-online/id1244948123

  Tech: iOS, Swift, Twilio, NSOperationQueue, AVFoundation / audio messaging

• iOS Developer (Contractor)

  Toogethr · Netherlands

  2021 – 2022

  Two companion apps — a car rideshare app and a bicycle group ride app — both rewarding users with discount coupons for kilometers travelled. Collaborated cross-functionally with Android, backend, and QA to align API contracts and ship stable releases.

  • Car rideshare: built reusable animated loading/progress system (LoadingBar, LoadingBarEngine, ProgressViewPresenter) with pause/resume via memento state, fast-forward, and timeout behavior
  • Car rideshare: contributed to domain features — suggestions/alternative matches, request handling, ride details/edit flows, and history presentation
  • Car rideshare: worked on reward-linked experiences (credits/rewardshop) and ride-state-driven UI updates; supported geofence and push-triggered refresh paths
  • Bike share: consulted and implemented full Autotracking end-to-end — calendar-style timeslot picker, AutotrackingServiceRegistry, push and local notifications for start/stop and travel reminders
  • Bike share: centralized bike ride recording into RecordService (timers, pause/resume/stop, location-driven tracking) with backend sync including challenge/points updates
  • Built points & rewards experience: credits in Ride History, challenge progress UI, and Rewardshop redeeming credits/coupons
  • Extended Core Data models for autotracking state and challenge/points data; added tab bar and profile image badges for settings/autotracking and ride/match states
  • Improved LocationManager authorization for iOS 14+; shipped dedicated GPS + battery settings screens
  • Added custom remote logger with periodic log upload; UI polish including animated progress indicators and account deactivation flow

  Tech: iOS, Swift, Core Data, Core Location, Push Notifications, Local Notifications, geofencing

• iOS Developer

  Doctor Care Anywhere · UK

  2020 – 2020

  Telehealth white-label apps — Swift / Objective-C · HL-7 diagnostics, network modernization, identity verification.

  • Initiated network-layer modernization: extracted auth and token refresh from a singleton request controller into reusable Swift request objects and a concurrent backend service framework
  • Applied dependency injection and coordinator patterns to separate API access, presentation logic, and legacy Objective-C controllers in a hybrid codebase
  • Implemented patient-facing HL-7 lab result screens: JSON parsing, filtering of invalid result types, contextual clinical notes, and branded UI across multiple app variants
  • Optimized Onfido-based identity verification by eliminating redundant verification triggers and tightening flow control during signup and family-plan onboarding
  • Shipped signup analytics (Mixpanel), email validation, and UI consistency fixes across 12+ appointment and prescription screens in a multi-target Xcode project
  • Supported production stability during platform upgrade work (iOS 13 push notifications, login flow, splash-screen refactoring)
  • Provided technical guidance to teammates on refactoring strategy, test design, and incremental ObjC→Swift migration
  • App Store: https://apps.apple.com/gb/app/doctor-care-anywhere/id882607302

  Tech: iOS, Swift, Objective-C, UIKit, XCTest, Coordinator pattern, MVVM, CocoaPods, White-label apps, Telehealth, HL7, REST API, OAuth / token refresh, Onfido, Mixpanel, iOS 13 migration, Obj-C/Swift interoperability, Multi-target Xcode projects

• iOS Developer

  Alfies Logistics (M&I Systems) · Austria

  2019 – 2019

  Driver app for Austrian online grocery delivery. Modernized legacy Swift codebase; rebuilt API client and offline photo upload system.

  • Led iOS modernization of Alfies driver logistics app (Swift 5 migration, API refactor, legacy code removal)
  • Architected offline-first photo upload pipeline — custom camera UI, Core Data persistence, concurrent disk I/O, background URLSession uploads with crash recovery and orphan cleanup
  • Rebuilt networking layer with typed request objects, message queues, retry logic, and location/device-enriched API headers
  • Delivered delivery workflow features — billing confirmation, deposit photo capture, customer-unreachable handling, and order list UI redesign
  • Improved app reliability — state resumption after process death, upload race-condition fixes, concurrent media upload, and unit tests for storage/upload paths

  Tech: iOS: UIKit, Storyboards, UIImagePickerController, Core Data, OperationQueue, background tasks · Networking: REST JSON APIs, multipart uploads, custom headers, error/retry handling · Patterns: Service registry/DI, DAO, protocol-oriented design, presenter patterns (ParkingPresenter, AlertPresenter) · Domain: Last-mile logistics, driver workflows, cash-on-delivery billing

• Mobile Developer

  ETNA Software / Sterling Trader (M&I Systems) · Serbia

  2018 – 2021

  White-label stock trading platform owner — iOS and Android brokerage apps with real-time sockets, charts, and complex ticker screens.

  • Created new brokerage white-label targets (Wedbush, Lightspeed, HR Trader, Traders Elite, StoneX), each with independent bundle IDs, API endpoints, branding, privacy policies, and Watch apps; documented the full target-duplication process
  • Feature development across ticket streams — position column customization, quote exchange metadata, operational-hours alerts, account info widgets, configurable trade screens, order lifecycle edge cases
  • Extended shared WebSocket data providers for Time & Sales and Market Depth; converted legacy Unitt WebSocket static libraries to XCFramework for Xcode 12 compatibility
  • Release engineering — version bumps, signing configs per brand, force-update via remote config, App Store / Play Store readiness
  • Xcode 10→12 migration; Android Studio / API level upgrades (targetSdk 28→30); migrated crash reporting from Fabric/Crashlytics to App Center
  • Trading features: Time & Sales, Market Depth, multileg options, Buy Back flow, ghost orders, order rejection banners, Account Info expandable sections
  • iOS-specific: iOS 13 compatibility, safe-area tutorial refactor, Launch Storyboards, UIAlertController migration, Apple Watch assets per target
  • Android-specific: HR Trader and Traders Elite Gradle flavors end-to-end; ApplicationConfigurator and position table improvements
  • Built Android app for field supply management with large database-backed article lists; mentored a junior developer
  • App Store: https://apps.apple.com/us/app/sterling-trader/id960316454

  Tech: iOS, Android, Swift, Java, WebSocket, XCFramework, App Center, white-label Xcode targets / XCConfig, Gradle flavors, Apple Watch, manual frame layout

• Lead iOS Developer

  Playerhunter · Germany

  2017 – 2018

  Led the iOS v2 rewrite from scratch after inheriting an unusable Swift prototype — architecting and implementing ~81% of the production app as the primary developer on a team of five.

  • Designed the entire app architecture: Service Registry with 15+ lazy-initialized domain services, protocol-based REST API layer, Core Data DAO layer, and NSOperation-based media upload pipeline
  • Built complete authentication and onboarding: email/password, Facebook, Google, and LinkedIn social login with email verification
  • Implemented advanced multi-tab search (People / Jobs / Pages) with filters and recent search persistence
  • Built the jobs marketplace end-to-end: job creation and editing, applications, applicant management, saved and applied jobs views
  • Developed social feed with posts, comments, likes, and link preview fetching
  • Built club/organization pages: creation, follower management, and activity feeds
  • Implemented connections system: invitations, suggestions, and contact import
  • Integrated Firebase push notifications with a notification service extension, Mixpanel analytics, and Crashlytics
  • Localized into 11 languages for the international sports market; shipped to the App Store as v2.39 with DEV/PROD build targets

  Tech: Objective-C, UIKit, Storyboards, CocoaPods, AFNetworking, Firebase, Mixpanel, Facebook/Google/LinkedIn SDKs, Applozic, SDWebImage, Crashlytics, PureLayout, Service Registry, NSOperation

• iOS Developer (Sole Developer)

  Timecode · Philip Morris / Marlboro 100's · Bosnia

  2016 – 2016

  Sole developer on an iPad field-marketing app deployed in cafés and local outlets for Marlboro 100's activations.

  • Built a puzzle-style pack assembly experience: users dragged and placed pack elements (rooftop, logo, sign, text) to build a complete cigarette pack
  • On completion, brand ambassadors used the app as part of a reward flow (customers received a promotional lighter)
  • Implemented core interaction in Swift/UIKit with custom gesture handling, positioning logic, and a CompositionEngine driving chained fade/move animations
  • Delivered separate Red and Gold product flows, extension animations (standard pack → 100's pack), and modal screens for product features
  • Built a plist-driven configuration layer so animation sequences and UI steps could be adjusted without rewriting code
  • Handled certificates, provisioning, and iterative ad-hoc builds through production IPAs used on event devices

  Tech: Swift, UIKit, Storyboards, Core Animation, gesture recognizers, iOS distribution

• iOS Developer

  Codecentric · Germany

  2015 – 2016

  One of three core iOS developers on WayGuard — personal safety with real-time location sharing, emergency triggering, and AXA guarding services. Also maintained white-label emergency reporting for German public insurers.

  • Owned the main companionship screen end-to-end: custom pulsing radial controls, friend/bodyguard selector, state-driven button animations, and a UI state machine for guarding/AXA states
  • Built user registration and onboarding: custom input components, validation, profile photo capture and upload, promo-code flow, and SMS confirmation
  • Developed PhotoService end-to-end: image upload, disk caching, thumbnail management, circular crop mask, and edit-profile integration
  • Delivered the emergency experience: swipe-to-trigger slider, countdown/progress UI, abort flow, map pin state changes, and police tips screens
  • Built in-app notification banner system for real-time peer status events with reconnect handling
  • Implemented invitation system, sliding side menu, settings, legal notice, and account deletion flows
  • Contributed early real-time WebSocket chat UI, AXA location/guarding integration, and HockeySDK crash reporting
  • OEV/GDV Unfallmeldedienst: maintained white-label emergency reporting iOS platform for 12+ German public insurers — Objective-C, Bluetooth LE, push notifications, Core Data, background GPS; smartphone-to-crash-sensor apps for automatic accident detection

  Tech: Objective-C, UIKit, WebSocket, HockeySDK, Core Location, Core Data, Bluetooth LE, push notifications, background GPS, AXA guarding integration

• Sole iOS Engineer

  CityZoom Guide · Serbia

  2015 – 2015

  7-language city tourism and lifestyle app shipped to the App Store; partnered with one backend developer.

  • Owned the full iOS product end-to-end: architecture, UI/UX, networking, MapKit, localization, analytics, and App Store delivery
  • Architected a modular Objective-C MVC codebase with 40+ view controllers, a service-layer REST client (15+ endpoints), and a reusable list/detail engine supporting 20+ content modes across 12 major sections
  • Built multi-category MapKit integration: custom POI annotations, category filtering, geolocation, route polylines, distance-to-venue, and handoff to Apple Maps
  • Delivered a business directory covering 40+ venue categories with basic and advanced multi-field search
  • Implemented runtime language switching across 7 locales (EN, DE, FR, RU, IT, SR, ES) with server-driven localized content
  • Built a dedicated LGBT city guide vertical (Rainbow Guide) with full feature parity with the main app
  • Delivered rich venue detail screens with multi-layout previews, image/YouTube/web carousels, embedded mini-maps, favorites, and one-tap contact actions
  • Built server-driven in-app notifications and full-screen promotional interstitials with image pre-caching; integrated Google Analytics and offline UX

  Tech: Objective-C, UIKit, Storyboards + XIBs, Auto Layout, MapKit, CoreLocation, AFNetworking, SDWebImage, NSOperationQueue, NSKeyedArchiver, CocoaPods, XCTest, Google Analytics, MONActivityIndicatorView, TSMessages, YouTube iOS Player

• iOS Developer (Contractor)

  Octotelematics · Italy / Netherlands

  2014 – 2015

  OctoDrive (white-labeled as 6sicuro / AAAD, including BNP Paribas-branded build) — telematics and driving-safety platform with GPS trip scoring and a social layer used by insurance partners.

  • Designed and built the friends and social-invite system from scratch: friend search, pending invitations, accept/unfriend flows, and Facebook-based friend discovery
  • Built the trip history module: calendar-based trip browser with scroll-to-today, trip categorization (Business / Entertainment / Night), and weekend/event styling
  • Implemented trip detail and map visualization: custom MapKit annotations, route callouts, and an expandable events list per trip
  • Led the iPhone 6 Plus migration across 50+ screens in a pre-Auto Layout codebase — size classes, device-specific XIBs, and a reusable sizing helper system
  • Delivered BNP Paribas (BNL) white-label branding: custom typography, color system, and redesigned registration and settings flows across a multi-target Xcode project
  • Multi-step registration flow (personal data, vehicle, city with Italian autocomplete), email/password login with password recovery, onboarding tutorials, and terms acceptance

  Tech: iOS, UIKit, MapKit, size classes, device-specific XIBs, Facebook SDK, multi-target white-label Xcode, telematics / GPS trip scoring

• Engine Developer

  Eipix Entertainment · Novi Sad

  2013 – 2014

  Sole mobile developer on the only mobile team (~10 people) within a 400-person studio, porting desktop Hidden Object/Puzzle Adventure titles to a cross-platform C++ engine (HoEngine/Kanji) for Big Fish Games.

  • Owned all iOS-side porting work: diagnosed and resolved platform-critical issues across a large monolithic C++ codebase — rendering, input, audio, video playback, mini-games, and payment flows
  • Debugged and patched the open-source Theora video library at the system level to fix broken seek functionality
  • Worked at native iOS SDK and OpenGL level for byte buffer and rendering issues
  • Acted as go-to consultant for Android, Windows, and Free2Play teams
  • Fixed critical iPad Mini crash on background/resume via selective GPU texture memory management
  • Implemented mobile inventory HUD touch hit-testing for core gameplay interactions
  • Integrated Big Fish Games iOS SDK (strategy guides, localized wrapping IDs, publisher configuration)
  • Worked in C++, Objective-C, and a custom cross-platform game engine; shipped titles credited in-game on the App Store by Big Fish Games

  Tech: C++, Objective-C, OpenGL, HoEngine/Kanji, Theora, iOS SDK, Big Fish Games iOS SDK

• Software Developer

  Execom · wiTherm / m2m · Novi Sad

  2012 – 2013

  wiTherm native app for warehouse thermic sensors, plus the broader m2m / IoT environment around the product.

  • Developed the wiTherm native app (Objective-C, UIKit, storyboards) for iPhone and iPad (split-view on tablet)
  • Implemented user authentication, device list with live telemetry (temperature, battery, Wi-Fi status), and periodic refresh over HTTPS REST
  • Built device onboarding using TI CC3000 SmartConfig (first-time Wi-Fi provisioning from the phone, session-based setup with backend)
  • Delivered historical readings UI and time-series charts (Core Plot); remote device configuration (sampling interval, reporting interval, alarm threshold)
  • Also contributed to the embedded side: wrote low-level memory management routines in mikroC for the sensor microcontrollers
  • Integrated Apple Push Notifications (device token registration with server)
  • Broader m2m environment — end-to-end IoT stack: Scala/Jersey REST API, MongoDB, MQTT messaging; Atmel firmware with CC3000 and MQTT; Java SmartConfig library; device simulator and integration tests

  Tech: Objective-C, UIKit, Storyboards, Core Plot, TI CC3000 SmartConfig, HTTPS REST, Apple Push Notifications, mikroC, Scala/Jersey, MongoDB, MQTT, Atmel, Java SmartConfig

• Software Developer

  Execom · KNVB and Eredivisie · Novi Sad

  2012 – 2013

  Stadium seat availability dashboard.

  • Built iPad dashboard for stadium seat availability in a multi-club football ticketing system (KNVB and Eredivisie sales entities)
  • Integrated SOAP/gSOAP client with T2M back-office APIs (ibus.chess.nl) for products, competitions, matches, and venue layouts
  • Implemented OpenGL ES 2.0 rendering pipeline for interactive stadium maps, seat states, and availability legend
  • Delivered UIKit navigation flow: login, sales-entity and product filters, and stadium visualization with EN/NL localization

  Tech: Objective-C, C, OpenGL ES 2.0, GLKit, UIKit, SOAP/gSOAP

• Software Developer

  Execom · Novi Sad

  2012 – 2013

  Custom C++ printer driver installer for an in-house printer solution.

  • Built a custom C++ printer driver installer

  Tech: C++

Skills

Education

• Informatics at Higher School for Business Studies (2002 – 2005)