25+ years of working with a huge range of technologies, writing applications for different OS, developing databases and applications. 14+ years of developer software for Apple devices. 10+ years of remote collaboration with the USA and Europe customers - e-commerce, health area, startups etc. My area is native apps and games (iOS/iPadOS/watchOS/tvOS/visionOS), and when it is needed, partnering with backend and Android engineers. My own projects are published on the App Store and you can find them in the portfolio below. If you need a quick and quality development - just ask me, we can discuss: - MVP of your idea - Refactoring and giving the second chance for your existing app - Migrating old project from Objective-C to Swift (UIKit/SwiftUI) - or any other

𝐀𝐫𝐞 𝐲𝐨𝐮 𝐥𝐨𝐨𝐤𝐢𝐧𝐠 𝐟𝐨𝐫 𝐚 𝐫𝐞𝐥𝐢𝐚𝐛𝐥𝐞 𝐭𝐞𝐜𝐡 𝐩𝐚𝐫𝐭𝐧𝐞𝐫 𝐭𝐨 𝐛𝐮𝐢𝐥𝐝 𝐚 𝐪𝐮𝐚𝐥𝐢𝐭𝐲 𝐚𝐩𝐩 𝐭𝐡𝐚𝐭 𝐬𝐨𝐥𝐯𝐞𝐬 𝐛𝐮𝐬𝐢𝐧𝐞𝐬𝐬 𝐛𝐨𝐭𝐭𝐥𝐞𝐧𝐞𝐜𝐤𝐬 𝐨𝐫 𝐥𝐚𝐮𝐧𝐜𝐡𝐞𝐬 𝐧𝐞𝐰 𝐯𝐞𝐧𝐭𝐮𝐫𝐞𝐬? How I Can Help You Succeed: - Full-Service Development: From initial concept to fully functional apps, I handle the complete development of mobile and web applications with a focus on delivering tangible results. - UI/UX Expertise: I offer intuitive design, app branding, and product workshops to ensure your app is not only functional but also visually appealing and user-friendly. - Long-Term Support: I build scalable apps, maintain them, and provide ongoing support to adapt to your business needs as they grow. - Cloud Solutions: Seamless integration with cloud infrastructure for performance, scalability, and reliability. How I Can Apply My Experience to Help You: Thanks to the success of my past apps, I became an Implementation Partner of RevenueCat (revenuecat.com) in 2022—a leading platform processing over $5 billion annually and powering 30,000+ apps worldwide. This partnership allowed me to work on apps with thousands of users and significant revenue, equipping me with valuable insights. I’d love to share what I’ve learned with you. Growth Results: - Helped clients generate over $2M annually by integrating RevenueCat. - Grew a client’s app revenue to $280K/year using Stripe. Services - UI/UX design, product workshops, app branding - iOS and Android app development - Web app development: frontend and backend - Maintenance, new feature development Your success is my focus, not just for the initial project but for the long term. Next Steps: Invite me to your project or message me now to discuss your ideas further. I’m offering a FREE strategy consultation call, where you’ll receive: ☝ Expert feedback on your project from an app payments specialist. ✌ Practical advice on development and app growth strategies. ✋ A rough estimate of project costs and timelines. ★★★★★ “It's rare to find somebody with deep knowledge about development, UX design and marketing of mobile apps. Marcin took the time to answer all of my questions and address my concerns. Amazing consultation!” - Viktoriya M. (viktoriyamart) I’m happy to share my expertise and explore how we can collaborate effectively. Contact me today to get started!

If your iOS app isn’t actively maintained, it’s already at risk. I help businesses keep their iOS apps stable, compliant, and running reliably through every iOS update — without the stress of crashes, App Store rejections, or production issues. Most apps work well at launch. Problems come later: iOS updates introduce breaking changes Bugs surface in production App Store approvals become unpredictable No one is responsible for long-term stability That’s where I come in. 🔧 What I Do I focus on keeping existing iOS apps healthy and operational: Fix crashes, bugs, and performance issues Ensure compatibility with the latest iOS versions Handle App Store submissions and rejections Provide ongoing maintenance so your app stays reliable 🧱 Core Services iOS App Maintenance & Stability Ongoing updates for new iOS releases Crash monitoring and bug resolution Prevent issues before they impact users App Health Audits Identify risks and technical debt Separate true app defects from iOS limitations Provide clear, actionable recommendations Resolve urgent production issues Fix rejected apps and submission blockers Stabilize apps that are no longer maintained App Rescues 📈 Experience 20+ years in software engineering Delivered a 99% crash-free production app (American Association of Orthodontists) Extensive experience diagnosing real-world iOS behavior Trusted across healthcare and private sector applications 🤝 When to Reach Out Your app is crashing or unstable You’re preparing for App Store submission You haven’t updated your app in months You need someone to take ownership of maintenance If that sounds familiar, feel free to reach out — I’m happy to take a look.

Full Stack Senior Mobile Engineer with 11+ years of experience building and shipping production applications for iOS, Android, and API services. Background includes payment processing, real-time communications, navigation and logistics, and messaging, with deep expertise in offline-first mobile development and implementing native mobile capabilities.

🚀 Helping Startups & Businesses Build High-Quality Mobile Applications Hi, I'm a Senior Mobile App Developer with over 10 years of experience in designing and developing scalable mobile applications for startups, entrepreneurs, and businesses worldwide. I specialize in building high-performance iOS, Android, Flutter, and Unity applications that are secure, user-friendly, and ready for production. Over the years, I have successfully delivered business applications, eCommerce apps, healthcare solutions, educational platforms, booking systems, social networking apps, games, and enterprise applications. To ensure smooth delivery of every project, I work closely with a talented team of UI/UX designers, backend developers, QA engineers, and project coordinators. This allows us to handle projects of any size while keeping communication simple—you'll always work directly with me as your primary point of contact. My Expertise 📱 Native iOS Development (Swift, Objective-C) 📱 Native Android Development (Java, Kotlin) 📱 Flutter Cross Platform Apps 🎮 Unity Game Development 🧩 ARKit & Augmented Reality 🔥 Firebase 🔗 REST APIs 💳 Payment Gateway Integration 📍 Google Maps Integration 🔔 Push Notifications ☁ AWS & Cloud Services 🔒 Secure Authentication 📊 Admin Panels 🚀 App Store & Google Play Deployment Why Work With Me? ✔ Clean & Scalable Code ✔ Transparent Communication ✔ Weekly Progress Updates ✔ Long-Term Support ✔ Fast Response Time ✔ Quality Assurance ✔ On-Time Delivery If you're looking for a reliable developer who can transform your idea into a successful mobile application, I'd be happy to discuss your project. Let's build something amazing together. Mobile App Development iOS Android Flutter Swift Kotlin Java Unity Firebase REST API Google Maps Payment Gateway Push Notification UI/UX Figma

Innovative Tech Leader | 15+ Yrs | Microsoft and Amazon Alumni | Team Lead / Technical Project Manager | AI Systems, RAG, LLM Chatbots, Voice Bots, Microservices Expert Hello! Welcome to my Upwork profile! With over 15 years in tech, I've transitioned from full-stack development and design to leading and managing projects. Working with 7+ startups and 30+ clients since leaving the corporate world, I'm now a Team Lead ready to guide your project to success. My broad expertise includes: • Project management: Coordinating with developers, designers, AI engineers, SEO experts, and QA teams • Leadership: Guiding both in-house and client teams • Technical skills: PHP (Laravel, Livewire, Inertia, FrankenPHP), JavaScript, mobile development, UI/UX design, and modern AI-driven application development • AI and automation experience: RAG applications, LLM based chatbots, voice bots, AI calling assistants, AI agents, and microservices based systems • Communication integrations: Twilio, VAPI, Telnyx, and other telecom APIs • Backend and infrastructure experience: FastAPI, Python, NestJS, BunJS • Database technologies: PostgreSQL, MySQL, Supabase, Neon Leading your team or my own, I make sure projects run smoothly from start to finish. My experiences at Microsoft and Amazon have shaped my career, and I've worked with 7+ startups and 30+ individual clients, creating and enhancing digital solutions. Now, as a Project Manager, I aim to use my diverse skills to help your projects succeed. In my free time, I still enjoy coffee and retro video games, keeping the fun alive. I am proud of my 5-star feedback on every project and a focus on quality that resonates with a 94 percent client recommendation rate and a perfect Upwork rating. I am ready to help you meet your goals with dedication and a creative touch.

Need a high-performance app that scales? 🚀 I build $0 to $1M MVPs for Tech Startups. With 14+ years of experience and a Top Rated status, I specialize in taking complex ideas and turning them into polished, production-ready mobile and web applications. If you are looking for a technical partner—not just a coder—I am here to help you move the needle. 🛠️ Expert Tech Stack ✅ Mobile: React Native (iOS & Android), Expo, Swift, Kotlin ✅ Web: Next.js 14/15, React.js, TypeScript, Tailwind CSS ✅ Backend/DevOps: Node.js, NestJS, Firebase, AWS, PostgreSQL, MongoDB ✅ Specialties: AI Integration (OpenAI/LangChain), Real-time WebSockets, Stripe/RevenueCat payments, and App Store Optimization (ASO). 🚀 Why Founders & CTOs Work With Me ✅ Full Ownership: I don’t just write code; I manage the deployment, CI/CD pipelines, and app store submissions so you can focus on the business. ✅ Performance-First: I build apps that are lightweight, fast, and optimized for user retention. Scalable Architecture: My code is modular and documented—ready for your future in-house team to take over when you grow. ✅ Clean Communication: 100% JSS reflects my commitment to transparency and meeting deadlines. 📈 Proven Track Record Built a SaaS platform from scratch that scaled to 50k+ active users. Modernized legacy codebases, reducing crash rates by 80%. Let’s build something world-class. Click the 'Message' button, and let’s discuss your roadmap. Keywords: Mobile App Development, Cross-Platform, SaaS Architecture, MVP Development, Full Stack Engineer, React Native Specialist.

8+ Years | iOS & macOS Development | Apps Delivered for Apple, Sony & Global Startups I help companies turn complex ideas into high-quality, App Store-ready applications. My focus: clean, maintainable Swift/Objective-C code and smooth user experiences. What I Offer: - Native iOS & macOS development (Swift, SwiftUI, Objective-C, C++) - UI implementation with UIKit & SwiftUI - App Store submission & compliance - API integration, data persistence, and performance optimization - Debugging & upgrading legacy codebases - System-level development (DriverKit, Endpoint Security Framework, BLE) Career Highlights: - Delivered iOS/macOS projects for **Apple** and **Sony** - Led development for multiple startups, from MVP to production - Integrated payment gateways, device APIs, and complex data flows - Successfully migrated apps to SwiftUI and modular architectures Communication & Work Style: I value clear communication, realistic timelines, and delivering results that work perfectly from day one. Available for both short-term projects and **long-term collaboration**. Let’s discuss your project — I’ll help you deliver a polished, stable, and user-friendly app.

When clients reach out, it's usually one of two things: they need something AI-powered built fast, or they need a senior engineering team to build something production-ready. I'm Aleksandr — I lead NerdHeadz, a product-focused AI and full-stack development agency. Over 12 years we've shipped LLM integrations, RAG systems, multimodal AI pipelines, and custom SaaS platforms across React, Python, and FastAPI. Recent builds: → AI adaptive learning platform — dynamic curriculum generation, quiz regeneration, behavioral adaptation (GPT + n8n + Supabase) → Investment intelligence platform — 3.6M+ companies indexed, thesis alignment scoring, portfolio risk modeling (Anthropic + Gemini + RAG) → Multimodal voice-to-book generator — multi-speaker detection, image-story alignment, print-ready export (GPT + Anthropic + CV) → Geofenced pet care marketplace — AI caregiver matching, background verification, ambassador growth engine You get me as your point of contact and a senior Eastern European engineering team executing — fast, async, outcome-focused. Fluxx 2025 AI Leadership Award · CXO Dubai 2025 · Clutch Top Developer 2024 · Stripe Partner Building something AI-powered? Let's talk.

I build automations that replace 20+ hours of manual work per week—connecting your CRM, sales tools, and operations into workflows that run themselves. As a Core Contributor to Shakey OS (Mobile AI Framework), I operate at the intersection of deep technical engineering and practical business application. While most automation "experts" rely solely on no-code tools, I bridge the gap by building custom middleware, API integrations, and LLM-powered agents that standard tools can’t handle. 🚀 Why Multi-Million Dollar Brands Work With Me: Enterprise-Grade Scale: I’ve architected systems for high-revenue companies that require 99.9% uptime and secure data handling. The Shakey OS Advantage: My deep involvement in AI framework development means I understand the "black box" of LLMs, allowing me to optimize for accuracy and cost-efficiency. Custom Software Roots: If a tool like n8n or Make hits a limit, I write the custom Python or Node.js code to break through it. 🛠 Core Capabilities: AI Agent Workflows: Designing RAG-based (Retrieval-Augmented Generation) systems that actually understand your company's data. End-to-End Automation: Full-scale orchestration using n8n, Make, and Zapier integrated with custom SQL databases. Custom SaaS Development: Building the "connective tissue" between your existing ERP/CRM and modern AI models (GPT-o1, Claude 3.5, Gemini). API Architecture: Designing robust, scalable APIs that allow your legacy systems to talk to the future. My process: We start with a 15-minute call to map your current workflow. I identify the highest-ROI automation opportunities, build a working prototype within days, and iterate until it runs flawlessly. If you're losing hours to repetitive tasks or your team is stuck copying data between tools, let's fix that.