Oleksandr Andreichuk, Developer in Lviv, Lviv Oblast, Ukraine
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Oleksandr Andreichuk

Verified Expert  in Engineering

Software Developer

Lviv, Lviv Oblast, Ukraine
Toptal Member Since
November 12, 2021

Oleksandr is a software engineer with extensive experience in native and cross-platform app development. He is skilled in native iOS, Android, macOS, Windows, and cross-platform mobile frameworks like Xamarin Native, Xamarin.Forms, and Flutter. Cross-platform and native development knowledge enables Oleksandr to perform a broad spectrum of work and create beautiful, fully functional applications for multiple platforms.


Windows Presentation Foundation (WPF), ReactiveX, Entity Framework Core, Win32
iOS, Android, Xamarin, Swift, HealhKit
Xamarin.iOS, Xamarin.Android, iOS Animations, Android Animations, Custom Views




Preferred Environment

Visual Studio, Git, Visual Studio Code (VS Code), JetBrains Rider, Xcode, Android Studio

The most amazing...

...contribution I've given is for the Xamarin.Forms project that is used by thousands of people.

Work Experience

Windows App Developer

2022 - PRESENT
  • Rectified memory leaks, resulting in a significant reduction in memory pressure for larger workplaces.
  • Resolved major synchronization issues caused by race conditions.
  • Implemented a variety of feature requests and bug fixes after the initial beta release.
Technologies: Windows Presentation Foundation (WPF), ReactiveX, Entity Framework Core, Win32

Mobile App Developer

2021 - PRESENT
  • Developed cross-platform SDK push notifications with offline message delivery handling.
  • Implemented an auto-generated networking layer based on OpenAPI specifications.
  • Developed an independent watchOS app built using Swift, SwiftUI, and Combine.
  • Built a unit and integration test suite for handling regressions.
Technologies: iOS, Android, Xamarin, Swift, HealhKit

Mobile App Developer

2018 - 2021
  • Implemented virtual classroom support for students and teachers.
  • Implemented audio recording for students and audio analysis for teachers.
  • Improved offline mode handling by introducing a performant caching layer.
  • Improved feature performance by more than 70% using more performant algorithms and data structures.
Technologies: Xamarin.iOS, Xamarin.Android, iOS Animations, Android Animations, Custom Views

Mobile App Developer

2019 - 2020
  • Converted native apps on iOS and Android platforms to Xamarin.Forms.
  • Implemented background location changes monitoring and geofence detection.
  • Implemented an augmented reality browser with points of interest location.
Technologies: Xamarin.Forms, Android, iOS, Augmented Reality (AR), Location Tracking, Maps, Geofencing

Mobile App Developer

2018 - 2018
  • Implemented indoor position tracking functionality.
  • Implemented wireless Bluetooth low energy (BLE) devices firmware updates.
  • Improved BLE beacon ranging and monitoring reliability.
Technologies: Android, Bluetooth LE, Bluetooth Beacons, Device Firmware Updates (DFU)

Cross-Platform App Developer

2011 - 2018
Dauntless Software
  • Developed a cross-platform framework for Android, iOS, Windows, macOS, and UWP apps that allowed the company to quickly build apps for all major platforms using a single codebase.
  • Migrated legacy native macOS/iOS (Objective-C), Android (Java), and PC (VB6) apps to the new cross-platform framework.
  • Created automated build scripts for building over 30 titles of the app for different platforms.
  • Implemented an internal crash reporting system that sends crash reports immediately and allows to check the apps' health and fix issues before any user complains.
Technologies: iOS, Android, MacOS, Java, .NET, Objective-C, C#, SQLite, Desktop, Mobile, ASP.NET Core, Offline Data Synchronization, Windows Presentation Foundation (WPF)

Pilot Logbook Application

A cross-platform electronic versatile pilot logbook system used by student and recreational pilots through senior airline captains and military pilots worldwide. It supports all major mobile and desktop platforms built from a single codebase.

Smart Office Application

A smart office application that optimizes workspace usage, enabling a better workday experience. It uses indoor location technology powered by BLE beacons that suggest the user's space based on their personal preferences.

Language Development Application

An educational, immersive language development application for mobile devices. It includes a rich user interface and smooth micro-interactions that help children learn languages at home and at school.
2006 - 2011

Master's Degree in Computer Engineering

Lviv Polytechnic National University - Lviv, Ukraine


Xamarin.iOS, Xamarin.Android, ReactiveX


Visual Studio, HealhKit, Git, JetBrains Rider, Xcode, Android Studio


.NET, Windows Presentation Foundation (WPF), Flutter, Cocoa, ASP.NET Core, StoreKit, Entity Framework Core


Xamarin, iOS, Android, Windows, MacOS, Visual Studio Code (VS Code), Desktop, Mobile, Bluetooth LE, Win32


Java, Objective-C, C#, Swift, Kotlin, F#, JavaScript, CSS, HTML


Functional Programming, Object-oriented Programming (OOP)




Algorithms, Data Structures, Xamarin.Forms, Augmented Reality (AR), Location Tracking, Maps, Geofencing, Bluetooth Beacons, Device Firmware Updates (DFU), iOS Animations, Android Animations, Custom Views, Offline Data Synchronization, Audio Recording, SVG

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