Senior Android Developer Kotlin / Java

The Job

We are looking for a Senior Android Developer to join our mobile team and build high-quality applications for international clients in Poland, the US and Europe.

Your Responsibilities

• Design, develop and maintain high-performance Android applications.
• Develop new features using Kotlin-first modern Android development.
• Maintain legacy modules written in Java when required.
• Design and maintain reusable Android libraries, SDKs, and internal frameworks used across multiple projects.
• Work with REST APIs, WebSocket, real-time data systems.
• Optimize app performance, memory usage, startup time and network efficiency.
• Write clean, maintainable, and testable code.
• Collaborate with backend developers, QA engineers, UI/UX designers and Project Managers.
• Participate in code review and technical discussions.
• Continuously evaluate and adopt modern Android technologies to improve development efficiency.

Tech Stack

Languages

• Kotlin (primary)
• Java (for legacy modules)

Architecture

• MVVM
• Clean Architecture
• Modular architecture (multi-module projects)

Android Jetpack

• ViewModel
• LiveData
• Navigation
• Room
• DataStore

Concurrency

• Kotlin Coroutines
• Flow
• Thread management & background processing

UI

• XML UI
• Jetpack Compose (preferred for new modules)

Networking

• RESTful APIs (JSON)
• WebSocket
• Retrofit / OkHttp (or similar libraries)

Database

• Room
• Realm
• SQLite

Cloud & Services

• Firebase
• AWS services (S3, SES)
• Google Maps API

Notifications

• Firebase Cloud Messaging (FCM)
• Pushwoosh

Tools

• Git / Git Flow
• Gradle
• Android Studio
• CI/CD pipelines (GitHub Actions, Bitrise, Jenkins or similar)

Core Requirements (Senior Level)

• 3+ years of professional Android development experience
• Strong experience with Kotlin
• Good knowledge of Java for maintaining legacy modules
• Strong understanding of:
  
  • Object-Oriented Programming (OOP)
  • SOLID principles
  • Android app architecture (MVVM / Clean Architecture)
• Experience with Android SDK and Android Studio
• Experience working with RESTful APIs and mobile networking
• Experience with offline storage and caching
• Experience with multi-threading, concurrency, and performance optimization
• Experience using Git version control
• Experience debugging complex issues and optimizing application performance

Nice to Have

• Experience building reusable Android libraries, SDKs, or internal frameworks
• Experience with modular Android architecture
• Experience with Jetpack Compose
• Experience working with CI/CD pipelines

Media Experience (Strong Advantage)

• Experience working with video streaming technologies
  
  • ExoPlayer
  • HLS / MPEG-DASH streaming
• Basic understanding or experience with DRM systems
  
  • Widevine DRM
• Experience integrating video player SDKs

Soft Skills

• Creative, ambitious and proactive mindset
• Strong problem-solving skills
• Good communication in English (reading and writing technical documentation)
• Team-oriented but able to work independently

Our Core Values

• We build quality and truly useful products that help people
• We prefer freedom and responsibility over rigid control
• We encourage creativity and innovation
• We make our employees more competent and valued every day

Benefits

• Attractive and competitive salary with annual review
• Opportunity to work with cutting-edge technologies
• Energetic, open and transparent working environment
• Unique and challenging projects with international clients
• Friendly international team using Agile methodology
• Company social and team-building events
• Flexible working hours