Hi there, I'm Jesús Marcano 👋

I am a Senior Mobile Architect with full-stack proficiency across Android (Kotlin) and iOS (Swift / SwiftUI), specializing in Payments SDKs and AI integration for Fintech, Healthtech, Entertainment, and Marketplaces.

9+ years building high-trust mobile systems at scale — including the Leboncoin Messaging module re-architecture (June – December 2025, 10M+ users) that cut response latency by 40%, native NFC/BLE payment modules across Android and iOS, and AI agents in production powered by LangChain/LangGraph.

I operate as a B2B contractor through Parallel Digital LLC — frictionless international compliance for EU, UK, and US clients. Based in Barcelona under the Spanish Digital Nomad Visa, remote-first, B1/B2 USA Visa.

I approach software engineering with the same discipline I learned as a professional Cellist: prioritizing structure, harmony between modules, and precise execution.

• 🔭 Current focus: Mobile-first AI integration — bridging native clients (Kotlin/Swift) and agentic backends (Python, LangChain, LangGraph, MCP, Claude, Gemini).
• 🛠 Building actively: Cross-platform mobile architecture with Kotlin Multiplatform (KMP), Payment SDK modernization, on-device + server-side LLM workflows.
• 🤝 Available for: Mobile platform architecture · Payment SDK / NFC integrations · AI-augmented mobile experiences · KMP adoption.

constjesus={mobile: ["Kotlin","Swift","SwiftUI","Kotlin Multiplatform (KMP)","Jetpack Compose"],ai_stack: ["LangChain","LangGraph","Claude","Gemini","MCP","RAG"],backend: ["Python","Haskell","Appwrite","Apollo GraphQL","REST","WebSockets"],payments_iot: ["Braintree","Google Pay","NFC","BLE (Bluetooth LE)","Payment SDKs"],architecture: ["Clean Architecture","MVVM","MVI","Offline-First Sync","State Machines"],infra: ["AWS","Docker","Firebase","CI/CD (Gerrit, GitHub Actions)"],testing: ["JUnit","XCTest","Espresso","TalkBack accessibility"]};

Mobile & Multiplatform

AI, Backend & Data

Payments, IoT & Hardware

• 💼 B2B contractor via Parallel Digital LLC (Ohio, USA) — clean compliance for EU/UK/US clients
• 🌐 Remote-first, Barcelona-based · open to hybrid in Barcelona
• 🇪🇸 Spain — Digital Nomad Visa (full work authorization)
• 🇺🇸 USA — B1/B2 Visa
• ⏰ Time zones served: CET (primary) · EU · UK · US East/West (with overlap)

I believe great engineering requires technical rigor and creative passion.

• 🎻 The Musician: Trained Cellist (Simon Bolívar Conservatory). I create musical arrangements and currently learning Piano. Music taught me that "synchronization" isn't just a thread concept — it's how teams succeed.
• 🌌 The Jedi: Huge Star Wars fan — the lore, the technology, the philosophy. This is the way.
• ✈️The AvGeek: Aviation enthusiast. I love planes and the engineering marvels that keep them in the sky.
• ⚽ The Fan: Loyal FC Barcelona (Barça) supporter. Visca el Barça!

Language enthusiast — learning new languages rewires the brain like new code paradigms.

• 🇺🇸 English — Professional Working Proficiency (C1)
• 🇪🇸 Spanish — Native
• (CAT) Catalan — Professional Working Proficiency
• 🇩🇪 German — Currently learning
• 🇫🇷 French — Future goal