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Denis123 123

@denis123123

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Android developer specializing in BLE & IoT, delivering production apps and connected hardware experiences.

Poland

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What I'm looking for

I’m looking for an Android role where I can own end-to-end features, especially BLE/IoT and connected-hardware workflows, ship production-quality apps, collaborate directly with clients, and keep modernizing architectures with strong CI and testing.

I’m an Android developer with 4 years of experience delivering production-grade mobile applications across marine safety, surveillance, medical, and e-commerce domains. I bring deep expertise in Bluetooth Low Energy—GATT protocols, custom beacon parsing, multi-device coordination, and OTA firmware updates over BLE—built end-to-end for real-world device ecosystems.

At Onix, I balance multiple client projects while owning greenfield builds and legacy modernization. I’ve shipped Android updates to 10,000+ combined end users, built a complete BLE stack for a marine safety product (custom advertisement parsing, multi-device coordination, OTA firmware updates), and reduced beacon detection latency by 40%.

I also create responsive, high-performance user experiences—like a real-time multi-camera monitoring app handling up to 16 concurrent streams with sub-second latency using FFmpeg and ExoPlayer. On the engineering side, I modernize architectures with MVVM, Clean Architecture, Koin DI, and robust testing using JUnit, MockK, and Espresso.

My embedded background (Arduino, ESP32, hardware assembly, and soldering) helps me build connected hardware–software products with practical insight. I’ve led complete feature delivery—from persistent background services and GPS-coordinated alerts in OLAS to iOS-to-Android ports with architecture modernization and maintained CI pipelines (GitLab CI + Docker), cutting build times by 30%.

Experience

Work history, roles, and key accomplishments

Current

Android Developer

Current

Onix

Jan 2024 - Present (2 years 6 months)

Delivered production Android apps across 4 concurrent client projects, shipping updates to 10,000+ combined end users. Implemented a BLE stack for a marine safety product, built a multi-camera monitoring app, ported an iOS app to Android, and improved CI build times with Docker-based GitLab pipelines.

Kotlin Android SDK Jetpack Compose MVVM Clean Architecture Koin DI ROOM WorkManager GATT GPS FFMPEG ExoPlayer Gitlab CI Docker OkHttp Apollo GraphQL REST APIs

Current

OLAS Marine Safety BLE System

Current

Onix

Dec 2023 - Present (2 years 7 months)

Developed the OLAS marine man-overboard alarm system Android app that detects and tracks BLE transmitters and triggers GPS-coordinated alerts. Built a complete BLE stack for 6 transmitter types, including BLE-based OTA firmware updates, foreground monitoring, and guided GPS recovery navigation.

Kotlin BLE GATT Custom Beacon Parsing Foreground Service Wake Lock Management ROOM WorkManager GPS

Medbee Medical Information App

Onix

Jan 2024 - Mar 2026 (2 years 2 months)

Developed and maintained the Medbee Android app providing access to structured medical reference data. Implemented an embedded WebView architecture with session caching, added unit and UI tests, and created push notifications for updated reference content.

Kotlin Android Junit MockK Espresso Push Notifications

OnlineCam Multi-Camera Monitoring

Onix

Jan 2024 - Feb 2025 (1 year 1 month)

Built an Android monitoring app for multiple IP cameras with low-latency live streams and an adaptive UI. Implemented multi-stream playback using FFmpeg decoding and ExoPlayer rendering, supporting up to 16 simultaneous feeds with smooth Jetpack Compose layouts.

Kotlin Jetpack Compose MVVM FFMPEG ExoPlayer

Group Purchase App (NDA)

Onix

Jan 2024 - Dec 2024 (11 months)

Ported a production iOS group purchase application to Android and modernized the architecture. Delivered feature parity across 50+ screens and enabled group purchases from multiple stores.

Kotlin Firebase

Android Developer Intern

Onix

Jul 2023 - Dec 2023 (5 months)

Onboarded onto production Android codebases and delivered first client-facing Kotlin features under senior mentorship. Progressed to a full Android Developer role within 6 months and took ownership of client projects.

Kotlin Android Development

Freelance Android Developer

Self Employed

Jan 2022 - Jun 2023 (1 year 5 months)

Built and delivered commercial Android applications for individual clients from requirements gathering through development to release. Worked hands-on with Kotlin, Retrofit, Firebase, and Material Design while completing varied client orders.

Kotlin Retrofit Firebase Material Design