Oleksandr is available for hire

Oleksandr Andreichuk

Verified Expert in Engineering

Software Developer

Lviv, Lviv Oblast, Ukraine

Toptal member since November 12, 2021

Expertise

iOS Android Xamarin .NET C#Swift Kotlin Algorithms Data Structures Augmented Reality (AR)Geofencing Offline Data Synchronization Windows MacOS

Bio

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.

Portfolio

Toggl

Windows Presentation Foundation (WPF), ReactiveX, Entity Framework Core, Win32

easierLife

iOS, Android, Xamarin, Swift, HealhKit

eKidz

Xamarin.iOS, Xamarin.Android, iOS Animations, Android Animations, Custom Views

Experience

iOS - 10 years Android - 10 years C# - 10 years Mobile - 10 years Desktop - 10 years .NET - 10 years Xamarin - 7 years Windows Presentation Foundation (WPF) - 5 years

Availability

Part-time

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

Toggl

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

easierLife

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

eKidz

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

Mapcite

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

OfficeLynq

Implemented indoor position tracking functionality.
Implemented wireless Bluetooth low energy (BLE) devices firmware updates.
Improved BLE beacon ranging and monitoring reliability.

Technologies: Android, Bluetooth Low Energy (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)

Experience

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.

Education

2006 - 2011

Master's Degree in Computer Engineering

Lviv Polytechnic National University - Lviv, Ukraine

Skills

Libraries/APIs

Xamarin.iOS, Xamarin.Android, ReactiveX

Tools

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

Platforms

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

Frameworks

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

Languages

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

Paradigms

Functional Programming, Object-oriented Programming (OOP)

Storage

SQLite

Other

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

Collaboration That Works

How to Work with Toptal

Toptal matches you directly with global industry experts from our network in hours—not weeks or months.

Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.

Start your risk-free talent trial

Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.

Top talent is in high demand.

Start hiring