Senior Staff Engineer with 16+ years architecting AI-native, event-driven distributed systems for global enterprises, startups, and fast-growing SaaS companies at scale. I've had the privilege of working with Bank of America, U.S. Bank, Fidelity Investments, TD Ameritrade, Verizon, and more, architecting platforms serving tens of millions of users and generating multi-million dollar revenues. My expertise spans React, React Native, Node.js, TypeScript, Python, and cloud-native infrastructure (AWS, GCP, Firebase), with deep specialization in LLM orchestration, RAG pipelines, agentic AI workflows, and streaming-first architectures. Beyond coding, I focus on performance, scalability, and intelligent automation, ensuring every system I build is designed to grow with your business. Why Clients Choose Me? ✔️ AI-First Architecture: Production-grade AI infrastructure, not wrappers. RAG, LLM orchestration, and agentic systems built for real-world load. ✔️ Tailored Approach: Every project is customized to fit your needs, scale, and budget. ✔️ Agile Workflow: Regular updates, milestones, and transparent communication. ✔️ High-Quality Engineering: Rigorous testing, performance optimization, and cost governance. ✔️ Proven Track Record: MVPs, SaaS platforms, AI-powered products, and enterprise systems at scale. Proven Results: ✔️ Bank of America: Built biometric login, mobile check deposit and stock trading features. 50M+ downloads, 46M active users, 4.8★ rating. ✔️ U.S. Bank: Co-defined the architecture for an AI-powered voice assistant. Led 22 engineers delivering React Native apps. 20M+ downloads, 5★ ratings, #1 ranking (Keynova Q1 2024). ✔️ Grax: Built SaaS platform from zero to $20M annual revenue, 100M+ API calls daily, scaled engineering org from zero to 40+ devs. Halved end-to-end latency via WebSocket streaming migration. ✔️ AI Logistics Platform: Developed AI-powered GPS navigation with LLM-driven route optimization, 100+ RN components, 10+ Node.js microservices on GCP. Industries I Cover FinTech and Banking · AI and Intelligent Automation · SaaS and Enterprise · Logistics and Transportation · Real Estate · Retail and E-Commerce · Media and Entertainment · Healthcare · Travel and Hospitality · Startups and MVPs What Clients Say Joel's expertise and leadership transformed our mobile platform. His ability to combine technical excellence with business focus is rare, and the results speak for themselves. Next Steps: Let's Build Something Intelligent Would you be available for a 30-minute free consultation? During this session we'll: ✔️ Review your project goals, AI opportunities, and technical needs ✔️ Outline a strategy, timeline, and cost estimate ✔️ Explore the smartest way to scale your product with AI-native architecture Ready to discuss your project? Send me a quick message and we'll book a 30-min consultation to map out goals, timeline, and budget. Looking forward to architecting something extraordinary together.

I am a Canada-based IT Systems Engineer currently managing enterprise infrastructure for a regional government organization in British Columbia. I specialize in Microsoft 365 tenant migrations, Azure AD hybrid environments, and security hardening for 10–200 employee organizations. At TNG, I re-engineered legacy Python data pipelines and maintain high-availability production infrastructure including VMware ESXi, Linux servers, and enterprise SharePoint systems. Previously, at ON2Solutions, I executed M365 and email-platform migrations with minimal downtime, implemented Barracuda email security, and deployed Intune MDM across multiple client sites. I bring Canadian government-level engineering standards to every project: secure, documented, and built to last. [Previous experience: Mobile application development (Flutter/Android) for early-stage startups, 2018–2020.]

Is your app slow, crashing, or expensive to change? I find out why, with evidence, and give you a plan your team can act on. Most of my work starts with a fixed-price app audit. I go through your codebase and your app for 7 to 10 days and deliver a scored report across 5 lenses: architecture, code quality, performance, stability, and delivery pipeline. You get the real risks, what each one costs you, and a prioritized fix plan with effort estimates. No lock-in. Your own team can run with it, or I carry out the plan as a fixed-price rescue project. I have been building iOS apps since 2017. Most recently I spent three years as a senior iOS engineer on a weather app used by millions of people, working on its performance and reliability. iOS is my core. I also audit and fix AI-built codebases (Lovable, Replit, Cursor and similar), Flutter, React Native, and native Android apps, and the backend behind the app. You can read a real 9 page sample audit on keystonesystems.eu/audit. It is the exact format you would receive. Fixed prices, published: Emergency Project Analysis: 1,500 euro, report in 5 days. AI-Codebase Audit: 2,900 euro, 7 to 10 days. Mobile App Audit: 2,900 euro, 7 to 10 days. Bigger scope quoted up front, never above 4,000 euro. Rescue and modernization: fixed-price phased project after the audit. My Project Catalog tiers are launch prices while I build my first reviews on Upwork. A lower tier covers less of your app. I audit whatever it covers to the same standard. The fixed prices listed here are my standard rates. If you are not sure the audit fits, send me a message and describe what the app is doing. I answer plainly, including when the honest answer is that you do not need me.

Expert Mobile App Developer | React Native & SwiftUI Specialist I'm a mobile app developer with 8+ years of experience building and scaling production apps in React Native, SwiftUI, and AI-powered products. My technical expertise spans JavaScript, TypeScript, SwiftUI, Expo, Next.js, and OpenAI API integrations, allowing me to build scalable, robust, and user-friendly apps tailored to your business needs. Key Achievements: - Credited Developer, Bat Around: Contributing gameplay and physics work to Bat Around, a live sports game on the App Store. - Founder & 2x Product Exit: Founded and personally built VidNotes (AI video transcription) end-to-end across iOS, Android, web, Chrome extension and backend, and grew it to a successful exit. Also built and sold AIVidly, an AI video, image and voice app. Two products built and exited independently. - Published App Store Apps: Designed, built and shipped FIFTN (screen time and focus, native SwiftUI with FamilyControls and DeviceActivity) and Coldsmith (cold exposure and breathwork with an Apple Watch companion) solo, under my own name. - Acquired Product Operator: Acquired and continue to operate Teleprompter X, a live creator app, handling subscriptions, release operations and ongoing development. - Leadership in App Overhauls: Led the complete redevelopment of the SNO Oslo app, introducing a new architecture and features like Personal Trainer lesson reservations. - Diverse Project Experience: Worked on mapping applications for large corporations, B2B solutions like Celebrate and Fitmate, and enterprise clients including Emirates Airlines. - Open Source and Writing: Created themegen.xyz, contribute to the React Native community with Sticky Parallax Header, and write technical articles for platforms like LogRocket. I am dedicated to creating exceptional mobile experiences that not only meet your needs but also delight your users. Let's collaborate to bring your ideas to life! Paweł Karniej

Hello! I’m Charlie, your expert for full stack development, analytics and HubSpot CRM management. 💎 “Any team would be lucky to have Charlie, and those he mentors will benefit from his exceptional leadership” Steven W - Full Stack Backend Engineer I bring a niche combination of technical expertise and startup guidance with a background as a software engineer and an MBA making me a great asset for any team. ★ CS/MBA ★ 20+ Applications ★ 1+ Million Shares (Unicorn Swag) ★ 20K WAU Techstars (Tripcents) ★ 10+ Years Experience in software development ★ Mindpaint: AI powered coloring pages behind a Stripe paywall. ★The Code Store: AI Boosted developer marketplace for monetizing packages. ★Forgeworks: AI Driven SaaS toolkit for revenue operations. ★MERN Architecture: Scalable multi-tenant applications. ★Backend: MongoDB preference. ★SDLC + Analytics 📝 Reviews: “Charlie developed an amazing application used by thousands of users. As a hands-on CTO, he mentored and hired additional developers while leading development himself. Charlie is not only a great developer but also an excellent teammate.” — Brantley P, VP of GTM, Events (formerly Hopin) “If I was picking a programmer to head my development team, Charlie would easily be my number one pick. A pleasure to work with, a pleasure to learn from and a pleasure to be around. Expert is an understatement when describing Charlie's skillset. Charlie has a knack for knowing the right time and right way to explain just about anything relating to code. Frontend, backend, side-end, doesn't matter, this is the guy that will point you in the right direction. I'm honored to worked beside this gentleman.” — Stanley M, Software Engineer, Designer & Author “Charlie is a great example of what a leader should be. He’s very knowledgeable, passionate, and dedicated to his craft in a way that’s unique to those who truly love what they do. I learned a lot from working with Charlie, which has empowered me to seek further career growth and refine my work. Any team would be lucky to have Charlie, and those he mentors will benefit from his exceptional leadership.” — Steven W, Full Stack Backend Engineer, 12+ Years of Professional Experience "Charles is the real deal. Our second contract went just as smooth as the first. His expertise in ios development and commitment was above and beyond my expectations. Each time we work together he brings new ideas to the table. His code and work ethic is unmatched. If your looking for someone who knows there stuff, is fair and easy to communicate with look no further. Highly recommend." - Tanner H, Upwork “Charlie has been a great CTO and engineer, comfortable digging in anywhere in the tech stack. I highly recommend having him lead your project to bring it to life or join your existing team to bring on some experienced engineering.” — Eli Z, Full Stack Web Developer, 8+ Years of Professional Experience “It's always a pleasure working with Charlie. Charlie is an experienced iOS developer and CTO. Not only does Charlie have the technical skills, but he also has an eye for recording talented developers and building strong teams. I look forward to continuing to work with him on current and future projects.” — Adrian O, Full Stack Web and Systems Architecture Specialist, 10+ Years of Professional Experience

25 years experience with 3 Microsoft certifications in Asp.net, C# and SQL. Full-stack Web and Mobile Developer - Developed 14 MVPs to date. Expert in .Net/C#, Blazor, Angular, React, Python and SQL

I am an AI-Integrated Mobile App Developer. I help startups and businesses build smart, high-performance iOS and Android apps powered by Artificial Intelligence including powerful machine learning capabilities (TensorFlow Lite, CoreML, or custom API integrations). Whether you need an app with an intelligent chatbot, image recognition, personalized recommendations, or automated data processing, I can build it securely and efficiently. What I bring to your project - End to End Mobile Development Clean, maintainable code for iOS and Android. - Practical AI Integration I don't just use buzzwords. I implement lightweight, on-device AI or connect seamlessly to cloud-based AI APIs (OpenAI, Google Vertex, AWS) to solve real business problems. - Clear Communication I provide regular updates, write clear documentation, and treat your project like my own. My Core Tech Stack -Mobile React Native, Flutter, Swift, Kotlin -AI/ML TensorFlow Lite, CoreML, Hugging Face, OpenAI API -Backend/Tools Firebase, Node.js, Python, RESTful APIs, Git I am highly motivated to build long-term relationships and earn 5-star reviews by delivering exceptional value.

Struggling with complex systems that don’t scale? As a Solution Architect with 15+ years of experience, I help businesses transform their platforms into reliable, high-performing solutions built on clean and future-ready architecture. Key facts about my experience: - Worked on 20+ projects across Hospitality, Retail, Healthcare, and Finance - Helped clients to build Business Analytics platforms using a Three-Tier Data Warehouse with Medallion-based architecture - Optimized ETL pipelines and data transformations to serve a dashboard with 20 unique reports and 600+ million filter combinations on over 10TB of data. - Designed and documented Solution Architectures for Highly Loaded systems, Data Engineering, and Machine Learning based systems. Core Technologies - Languages: Python, Go, Ruby, Javascript - Frameworks: Django, FastAPI, Ruby on Rails - Frontend: Hotwire, Tailwind, Vue.js, React.js, TypeScript - Databases: PostgreSQL, Redis, Snowflake - Cloud: AWS, Azure, DigitalOcean - Containerization & Orchestration: Docker, Kubernetes, Helm - Other: GraphQL, gRPC, RabbitMQ, WebSockets, WebRTC, CI/CD If you’re looking for someone who can design and deliver scalable architectures, optimize data flows, and bring structure to complex projects, I’ll help turn your requirements into robust, future-ready solutions. Explore my portfolio of recent projects completed together with my teammates at MobiDev, a software development and AI consulting company serving clients across North America and Europe.

10+ years of experience on Unix-based operating systems (MacOS, Linux) Deep knowledge of CPU architectures, memory management 10+ years of C++/Qt desktop GUI development experiences 5+ years of kernel driver, low-level communication protocol development 5+ years of RTOSes, baremetal systems, task scheduling and threading 10+ years of network communication and socket programming Extensive knowledge of web technologies and desktop software development Strong documentation, testing and coding skills Keywords: c++, embedded, opengl, git, cmake, gcc, clang, travis CI, unit test, java, Linux, android, ios, php, sql, c++11, c++14, c++17, agile, engineering, mathematics, physics

✦ You bring the idea. I bring it to life — beautifully designed, fully built, and ready to ship. From the first research session to a deployed, production-ready product — I cover the entire cycle with senior expertise at every stage and AI-optimised workflows that make it faster without making it worse. Design that's actually deep. Delivery that's actually complete. One engagement, zero gaps. 💬 How my team and I work with you: My designers work closely with you — not through layers of management. That relationship is how we get the UX right: we understand your goals, your users, your constraints, your product logic. The deeper we get into your world, the better the outcome. That's intentional, not accidental. 💡 What you get from this collaboration: ✅ Senior UX/UI designers with deep domain knowledge ✅ Production-ready design + frontend code from the same team — no handoff gap ✅ AI-accelerated delivery (Claude Code, Cursor, Lovable, Figma AI) that compresses timelines without cutting quality ✅ A working, deployed product - not a deck, not a static mockup 🔁 The full cycle, one team: 🔍 Discovery - UX research, user flows, personas, competitor analysis, product strategy & requirements 🎨 UI/UX Design - information architecture, wireframes, AI-generated style guide, full component library ⚙️ Working MVP - production-ready code, deployed to live URL, accessibility-checked, stakeholder-iterated 📁 Full Documentation - GitHub repo, architecture diagrams, API docs, developer handoff, acceptance criteria 🎯 Where we're strongest: 🔬 Healthcare & MedTech - clinical portals, patient-facing apps, medical SaaS, simulation interfaces - we know the constraints, the edge cases, and what good UX looks like when errors have real consequences 📊 B2B SaaS - dashboards, AI product interfaces, onboarding flows, complex data views 📱 Cross-platform - desktop, iOS, Android, responsive web - designed to platform conventions ⭐ Track record: ✅ 100% Job Success Score · ✅ Top Rated Plus· ✅ $100K+ on Upwork ✅ 5.0 on Clutch 📩 → Message me to start the conversation