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Ivan Ts., Lead Kotlin /Java Engineer
Ivan Ts.
🇺🇦Ukraine (UTC+02:00)
Created AtUpstaffer since October, 2025

Ivan Ts. — Lead Kotlin /Java Engineer

Expertise in Back-End Web, Android.

Last verified on October, 2025
Upper-Intermediate English

Bio Summary

Ivan is a Lead Kotlin/Java Engineer with solid experience in backend and Android development. He builds reliable and maintainable applications, works well with cross-functional teams, and enjoys improving codebases and system architecture. Ivan is comfortable mentoring others and contributing to both mobile and backend projects, making sure they run smoothly and efficiently.

- Software Engineer with 5+ years of experience in developing Android and backend solutions in the healthcare, fitness, and automotive industries;
- Strong Skills with Kotlin, Java, and TypeScript, creating Android applications on Jetpack Compose, Firebase, Android SDK, KMM, as well as backend solutions on Spring Boot (and basic experience with Node.js / React for integrations and prototypes);
- Experienced with AWS (Serverless, Lambda, S3, API Gateway) and GCP, builds cloud infrastructure, and is undergoing Google Cloud certification;
- Skilled with Firebase as a backend platform;
- Experience CI/CD, Docker, GitHub Actions, works according to Agile principles;
- Interested in implementing AI models in production solutions.

Technical Skills

Programming LanguagesJava, Kotlin
Android Libraries and ToolsAndroid SDK, Jetpack Compose, Kotlin
Mobile Frameworks and LibrariesCrashlytics, KMM
JavaScript Libraries and ToolsReact Hooks
Java FrameworksSpring, Spring Boot
Data Analysis and Visualization TechnologiesML
Databases & Management Systems / ORMFirebase, InfluxDB, MongoDB, MySQL, PostgreSQL, TimescaleDB
Cloud Platforms, Services & ComputingAWS, GCP
Amazon Web ServicesAWS Lambda, AWS S3
Azure Cloud ServicesAzure MSSQL
Methodologies, Paradigms and PatternsAgile, Kanban, MVC, OOP, REST, Scrum, TDD
PlatformsAndroid, Firebase
SDK / API and IntegrationsAndroid SDK, RESTful API
Third Party Tools / IDEs / SDK / ServicesAndroid SDK, JetPack
QA, Test Automation, SecurityApache Maven, JUnit, Mockito, Selenium, Selenium Webdriver, TestNG
Collaboration, Task & Issue TrackingAtlassian Confluence, Jira
Deployment, CI/CD & AdministrationCI/CD, Gradle, Jenkins
Virtualization, Containers and OrchestrationDocker, Kubernetes
Version ControlGit, Github Actions
Mail / Network Protocols / Data transferGRPC, HTTPS, WebSockets
Message/Queue/Task BrokersKafka
UI/UX/WireframingUI/UX
Other Technical SkillsProtobuf

Work Experience

Lead Engineer, Box12

Duration: May 2024 - Present

Summary:Leads the development of an ecosystem of fitness applications and services that enhance user experience and engagement in gym training. Responsible for full-cycle architecture design, development, and team leadership.

Responsibilities:

  • Designed and implemented mobile app architectures using Jetpack Compose and MVI.
  • Managed a cross-functional team of 5 (Android, Backend, QA, DevOps).
  • Conducted mentoring sessions, introduced performance metrics and reward systems.
  • Rebuilt the legacy codebase to improve scalability and user experience.
  • Focused on user retention strategies through UX optimization.

Technologies: Kotlin, Android SDK, Firebase, Jetpack Compose, Jetpack Multiplatform Mobile, Retrofit, Koin, Room, Coroutines, Flow, GCP, Google Material Design, PostgreSQL, Firebase, Jira, GitHub, Confluence, Android Studio, GCP Console, Cloud AI.

Back-end Kotlin Engineer, Capgemini Engineering

Duration: Jun 2023 - Apr 2024

Summary:Developed backend solutions for AI-powered healthcare systems serving Indian clinics and hospitals. Focused on performance, distributed systems, and data optimization.

Responsibilities:

  • Built API solutions using Kotlin, Spring Boot, and PostgreSQL.
  • Integrated TimeScaleDB for 10x faster data processing and 3x space efficiency.
  • Implemented Kafka-based asynchronous workflows and Keycloak authentication.
  • Reduced DB load by 20% through caching decoupling and configuration service optimization.
  • Maintained production monitoring and compatibility across distributed systems.

Technologies: Kotlin, Java 21, Spring Boot 3.2.2, Spring 6+, Keycloak, FHIR, Retrofit, Kafka, JUnit, Mockito, Jenkins, Oracle, PostgreSQL, TimeScaleDB, Jira, GitLab, Confluence, IntelliJ IDEA, Checkstyle, Figma, Excel, Swagger.

Back-end and Android Engineer, Globallogic

Duration: Jan 2022 - May 2023

Summary:Worked on Java/Kotlin desktop and Android applications for global telecom (Verizon) and healthcare (Samsung) clients, including AI and voice assistant integrations.

Responsibilities:

  • Developed Kotlin Multiplatform Mobile (KMM) apps with Jetpack Compose and Firebase.
  • Built full-stack features across web and desktop using JavaFX/TornadoFX.
  • Integrated Amazon S3, AWS Lambda, and GCP ML services.
  • Ensured product stability and rapid feature delivery through CI/CD pipelines.

Technologies: Kotlin, Java 17, Firebase, JavaFX, TornadoFX, KMM, Jetpack Compose, Ktor, Retrofit, Dagger, RxJava 2, Coroutines, Flow, AWS (S3, EC2, Lambda, ECS), PostgreSQL, Firebase, Jira, GitLab, Confluence, IntelliJ IDEA, Android Studio, Docker, AWS Console, Amazon S3.

Back-end Software Engineer, Business Information & CrowdFund Platforms

Duration: Apr 2021 - Dec 2021

Summary:Built scalable backend systems for business information management and a crowdsourcing platform. Contributed to BikeShare Ireland backend and enrichment systems.

Responsibilities:

  • Developed RESTful APIs using Java and Spring Boot.
  • Applied TDD and best practices for backend quality assurance.
  • Supported existing platforms and built new features from scratch.
  • Participated in low-level design discussions and architecture improvements.

Technologies: Java 11, Spring, Spring Boot, Maven, SQL, REST, Mockito, Tomcat, TypeScript, Angular CLI, PostgreSQL, MySQL, Jira, Bitbucket, Confluence, SonarQube, IntelliJ IDEA, Checkstyle, Docker.

Big Data Java Developer, BMW

Duration: Jul 2019 - Mar 2021

Summary:Worked on a large-scale big data solution for the BMW automotive sector, focusing on analytics, data processing, and system optimization.

Responsibilities:

  • Built and optimized SQL-based analytical pipelines using Apache Spark.
  • Developed scripts for data migration between Spark and Spring.
  • Refactored legacy code, improving maintainability and reducing technical debt.
  • Participated in developer training and feature enhancement initiatives.

Technologies: Java 8, Apache Spark, Tomcat 8.5, MySQL, Bitbucket, Jira (Scrum + Kanban).

Software Engineer, “Glory to the Nation Foundation”

Duration: Jan 2019 - Apr 2019

Summary:Developed a data-sharing system for public procurement transparency.

Responsibilities:

  • Built C#-based desktop modules with MSSQL integration.
  • Designed reporting and statistical visualization features.

Technologies: C#, MSSQL, WPF, WinForms, ASP.NET, Entity Framework, GitHub.

Software Engineer, Estella

Duration: Jul 2018 - Jan 2019

Summary:Developed software for managing furniture warehouse operations.

Responsibilities:

  • Built both desktop and web versions of warehouse management tools.
  • Integrated business logic and database layer for inventory operations.

Technologies: C#, MSSQL, WPF, WinForms, ASP.NET, Entity Framework, GitHub.

Work Sample

Vide - Event Interaction Platform (Commercial Project)

Client: Confidential

Platform: Android

Summary:Commercial Android application developed for a client. The product provides functionality for managing events, sessions, and targets within an interactive media environment.

Role:Engineer in the development team.

Technologies:Kotlin, Android SDK, Jetpack Compose, Firebase, GCP

Examples:https://drive.google.com/drive/folders/1I_Z622qV1BgGle68Db7qdgB098-14U8Y?usp=sharing

Education

  • Master’s Degree in Software Engineering,Polytechnic National University (NULP) (Graduation Year: 2019)
  • Bachelor’s Degree in Software Engineering,Polytechnic National University (NULP), Ukraine (Graduation Year: 2017)

Licenses & Certifications

  • Google Cloud Professional Cloud Developer
  • Coursera: Software Design and Architecture
  • Bobocode: Kotlin Developer Path
  • Mastermind: Android Architecture Advanced

Mentoring & Leadership

  • Mentor at Bobocode Academy, guiding junior developers in Kotlin and backend development;
  • Conducted internal tech sessions on Kotlin Multiplatform, Spring Boot, and Clean Architecture;
  • Supervised a team of 5 developers and led system design reviews across multiple projects.

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Ivan Ts., Lead Kotlin /Java Engineer
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