Sergey K.

20+ years in native Android. 100+ apps launched, 20M+ downloads, and a 4.8+ average rating. I build, optimize, secure, and scale high-performance Kotlin/Java apps - from complex mobile products and streaming to fintech, AR, BLE & enterprise systems. 👋 Hi there ! Looking for an elite Senior Android Developer to architect, secure, and scale powerful Android applications? With 20+ years in native Android development, I've worked across every major SDK, library, and device evolution - delivering fast, secure, and maintainable apps that perform under pressure. I’ve developed and launched 100+ Android apps with over 20 million total downloads and an average Google Play rating of 4.8+. My work has helped reduce crash rates by 70%, shrink APK sizes by up to 60%, and increase app startup speed by 45%. From startups to Fortune 500s, I’ve led 12+ dev teams in delivering mission-critical, high-ROI apps for fintech, defense, media, and beyond. 🏆 Why Work With Me for Android Development? ✔️ 20+ years of deep Android expertise with Java, Kotlin, Jetpack, and NDK ✔️ Delivered 100+ apps to production — 20M+ installs, 4.8+ average rating ✔️ Reduced load times by 45% through advanced performance profiling ✔️ Security-hardened apps using R8, ProGuard, LLVM, NDK, and SELinux policies ✔️ Scaled enterprise-grade apps with 99.99% uptime and real-time data sync ✔️ Played key roles in HIPAA-, FIPS-, and PCI-DSS-compliant mobile solutions 🚀 Core Android Development Services: 📌 Native Android App Development 🔹 Expert in Kotlin, Java, Android SDK, Jetpack Compose, View System 🔹 Responsive UIs across all screen sizes using ConstraintLayout, MotionLayout, Compose 🔹 Modular architecture (MVVM, Clean Architecture, MVI, VIPER) 🔹 Advanced state handling with LiveData, Coroutines, Flow, RxJava 🔹 CameraX, MediaCodec, ExoPlayer for media-heavy apps 🔹 Full device compatibility from Android 5.0+ through latest Android 14 📌 Android Security & Low-Level Optimization 🔹 Obfuscation, code hardening, and NDK-level protection 🔹 Reverse engineering mitigation via Frida/Root detection 🔹 Low-level optimization with ARM NEON, RenderScript, JNI, and custom kernels 🔹 SELinux customization for hardened AOSP builds 🔹 Hardware integration with sensors, gyroscopes, accelerometers, and BLE 📌 Multimedia, Games & Streaming 🔹 Real-time video/audio with FFmpeg, OpenGL, Vulkan, MediaCodec 🔹 Game engines: Unity3D, LibGDX, custom OpenGL renderers 🔹 Augmented Reality with ARCore, face tracking, 3D overlays 🔹 Advanced drawing tools, canvas-based animation, real-time filters 📌 Backend Integration & Architecture 🔹 REST, GraphQL, gRPC, WebSockets, Firebase, and custom socket protocols 🔹 Secure data sync, push notifications (FCM), and analytics (Firebase, Amplitude) 🔹 CI/CD pipelines using Jenkins, Bitrise, GitHub Actions, and custom Gradle workflows 🔹 Offline sync and caching strategies for resilient performance 📌 Scalable Architecture & Cross-Platform 🔹 Kotlin Multiplatform, Clean Architecture, modularized multi-feature apps 🔹 Deep understanding of Android App Bundles, Play Feature Delivery, and Instant Apps 🔹 Flutter experience for select cross-platform needs (Dart/Flutter SDK) 📌 Database & Networking 🔹 SQLite, Room, Realm, SQLDelight, Firebase Realtime/Firestore 🔹 JSON parsing with Gson, Moshi, org.json 🔹 API integration using Retrofit, OkHttp, Apollo Client 🌟 Results-Driven Impact ✅ 70% reduction in crash rates using advanced testing and monitoring ✅ 45% increase in startup speed through bytecode and resource optimization ✅ 60% smaller APK sizes using modularization and build optimization ✅ 50% faster delivery cycles using custom CI/CD pipelines ✅ 40–65% increase in user retention through performance and UX refinement ✅ 99.99% stability in live apps with over 1M monthly active users 💡 Focused On What Matters Most: ✔️ Clean, scalable, testable code that teams can maintain and extend ✔️ Proactive debugging and crash prevention strategies ✔️ User-first experiences built for performance and engagement ✔️ Modern, maintainable app structure that grows with your business ✔️ Full lifecycle support-from idea to Play Store launch and beyond 🚀 Ready to Build a High-Performance Android App? Let’s talk! Whether you're starting from scratch, rebuilding a legacy app, or scaling for millions-I'll help you build it right, fast, and with precision.