Juan H.
Senior Android & KMP Engineer | Performance & Architecture Specialist
Senior Android Engineer with over 14 years of professional experience specializing in high-performance mobile systems, scalable Kotlin Multiplatform (KMP) architectures, and complex SDK development. I excel at dropping into established codebases to untangle legacy dependencies, optimize system performance, and deliver robust, production-ready features. Most recently, I worked as a Senior Consultant for SmartThings, where I designed and optimized core features for the MOBI SmartKit SDK. I specialize in IoT-driven mobile experiences where efficiency, low-latency parsing, and solid architecture are absolutely critical. Beyond product engineering, I have a deep passion for compiler-level optimizations, KSP/KSP2, and low-level performance tuning. I am the creator of Ghost Serializer, an open-source, byte-first JSON serialization engine built for Kotlin Multiplatform that drastically reduces heap memory allocations by over 50% and speeds up API throughput by up to 66%. I bring this exact compiler-level understanding of the Android platform to every project I take on. How I can help your project: Complex Legacy Migrations: Upgrading older Android SDKs, libraries, and codebases safely without breaking production. SDK & Library Development: Building highly optimized, developer-friendly tools and libraries for internal or public use. Extreme Performance Tuning: Debugging memory leaks, reducing Garbage Collection (GC) overhead, and optimizing network/serialization layers. Kotlin Multiplatform (KMP): Architecting cross-platform data and domain layers to share business logic seamlessly between Android, iOS, and backends. Third-Party Integrations: Implementing complex, state-heavy SDKs (e.g., IoT protocols, WalletConnect/Web3, secure payment gateways). Core Tech Stack: Mobile: Android SDK, Kotlin, Java, Coroutines, Jetpack, KMP Architecture & Performance: KSP2, Memory Optimization, Bytecode-level tuning Backend & Tooling: Spring Boot, Ktor, Git, CI/CD Whether you need to architect a new mobile application from the ground up, scale an existing platform, or squeeze maximum performance out of a critical data path, I bring the technical vision and hands-on expertise to deliver exceptional results. Let's build something incredibly fast and reliable.
Earnings and projects
Last 6 months ÷ 6
Last 6 months: $41k
Billed in all: $431,366$431k
$14k in the last 6 months
Across 18 contracts
Earnings, last 30 days
Skill rankings: #1 in 1 skill of 9
Rarest: top 0.75% in Android SDK, of 805. Ranked by MRR among everyone on Upwork with the skill.
- Dependency Injection Framework36 freelancers · 🇸🇻 #1Top 3%🇸🇻#1 of 1
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- #6Android SDK805 freelancers · 🇸🇻 #1Top 0.75%🇸🇻#1 of 1
- #32Software Architecture964 freelancers · 🇸🇻 #1Top 3%🇸🇻#1 of 1
- #40Kotlin3,021 freelancers · 🇸🇻 #1Top 1%🇸🇻#1 of 2
- #66Android4,975 freelancers · 🇸🇻 #1Top 1%🇸🇻#1 of 4
- #67Git5,766 freelancers · 🇸🇻 #1Top 1%🇸🇻#1 of 3