We Build Next Generation of Mobile Applications Senior Mobile Lead Engineer | 9+ years of experience | High-quality Mobile and Web Apps | Claude Code 📊 My Core expertise is the Apple ecosystem, delivering robust solutions across iOS (Swift, SwiftUI), iPadOS, watchOS, and macOS. I work extensively with Swift, SwiftUI, UIKit, Combine, Objective-C, and advanced Apple frameworks such as HealthKit, MapKit, and complex third-party integrations. Beyond development, I provide end-to-end product delivery — from idea validation to App Store release. By combining Business Analysis, UI/UX Design, Agile Development, and Quality Assurance, we build future-proof applications that minimize technical debt and reduce long-term maintenance costs. ⸻ Services I can provide: 📱 Native Mobile Development (iOS & Android) • iOS Development: Swift, SwiftUI, UIKit, Combine, Objective-C • Android Development: Kotlin, Java • Cross-platform: React Native, Flutter • Apple Watch apps, smartwatch apps • Health & fitness apps, Apple Health, HealthKit • Maps & navigation (MapKit, Google Maps, Mapbox) • Real-time features, sockets, charts & analytics 🌐 Web Development • React, Angular, Next.js • TypeScript, JavaScript • High-performance front-end and responsive UI development 🛠 Backend & DevOps • Node.js, Python, Go, PHP • API development & third-party integrations • Cloud deployment: AWS, Docker, VPS 🎨 UI/UX Design & Product Thinking • Figma, wireframes, prototypes, user flows • Product discovery and idea validation before development 📊 Management & QA • Agile project management • Manual & automated testing • Business analysis & product ownership support ⸻ Fintech Expertise • Crypto applications (BTC, ETH, USDT, TRC20) • Real-time exchange data & socket connections • Charts, analytics, and on-chain operations • Secure authentication & sensitive data handling ⸻ Why Clients Choose Us ✔️ iOS-first team with deep expertise as Swift Mobile Developers ✔️ Reliable long-term partner for scalable product development ✔️ Strong focus on performance, usability, and clean architecture ✔️ Transparent communication and Agile processes ✔️ Full-cycle delivery: design → development → QA → release → support ⸻ Looking for a long-term Swift Mobile Developer instead of a one-off coder? If you need a stable, scalable, and carefully crafted mobile product built with modern iOS technologies, let’s discuss your goals. I can provide a clear project plan, timeline, budget estimate, and technical strategy tailored to your vision. ⸻ 🔑 Technologies & Keywords (SEO Optimized) Swift Mobile Developer, Senior Swift Developer, iOS Developer, SwiftUI, UIKit, Combine, Objective-C, Apple Developer, iPhone App Development, iPad App, macOS App, watchOS App, HealthKit, Apple Health, MapKit, Google Maps, Mapbox, Kotlin, Android Developer, React Native, Flutter, TypeScript, JavaScript, Figma, UI/UX Design, MVP Development, High-Quality App Development, Mobile Architecture, Performance Optimization, Scalable Mobile Apps, Crypto Wallet App, Bitcoin, USDT, tokens, Quality, high-quality app ⸻ 📩 Send me a message, and I’ll share my Upwork scheduler link so we can find a time that works best for you

🏆 Why I'm a Top-Rated Full Stack Developer & .NET Developer 8+ years as a Full Stack Developer and .NET Developer, 60+ web apps shipped for US, UK and EU clients
$60k+ earned on Upwork as a C# Developer and .NET Developer, 100% Job Success Score
 As a Full Stack Developer, I've shipped 40+ releases combining React, Angular and ASP.NET Core
 As a C# Developer, I cut API response times by 45% and infrastructure costs by 30% for a fintech client
As a .NET Developer, I migrated 3 legacy monoliths to .NET Core microservices, +70% deployment speed 💥 Recent win — as a Full Stack Developer and C# Developer, I rebuilt a logistics platform using .NET Core, Angular and MySQL, cutting order processing time by 55% and lifting client retention by 22%. 🟢 Most business platforms are slow, hard to scale and expensive to maintain. With 8+ years as a .NET Developer, C# Developer and Full Stack Developer, I architect scalable web developer solutions on .NET, Angular, React and Python stacks that turn technical debt into growth 🟢 ⭐️⭐️⭐️⭐️⭐️ "She's an outstanding .NET Developer and Full Stack Developer. Reliable, communicative, and delivers clean, production-ready C# code every time." 🎯 WHY CLIENTS CHOOSE ME AS A FULL STACK DEVELOPER I'm a Full Stack Developer, .NET Developer and C# Developer with full-cycle ownership — from database architecture and API design to pixel-perfect frontends. As a C# Developer, I write clean, testable code following SOLID principles, and as a Full Stack Developer I make sure the entire product actually works for your users. ✔️ .NET Core & C# — as a .NET Developer and C# Developer: scalable ASP.NET Core APIs, background services, .NET MAUI apps
 ✔️ Frontend — React, Angular, Vue.js, jQuery, built for speed and clean UX
 ✔️ Full Stack Development — as a Full Stack Developer, connecting .NET, Node.js and Python backends to JavaScript frontends
 ✔️ Web Developer Services — as a web developer, WordPress, Laravel and PHP sites alongside custom .NET apps
 ✔️ Database Architecture — MySQL, SQL Server, API Integration for data-heavy systems
 ✔️ Cloud & DevOps — Azure, AWS, Docker, CI/CD, supporting .net full stack developer and full stack developer react deployments 📊 RESULTS 🔶 Fintech Platform: as a .NET Developer and C# Developer, -60% transaction errors, 99.9% uptime via a full .NET Core rebuild
 🔶 E-commerce Marketplace: as a Full Stack Developer, React + .NET Core APIs, +28% checkout conversion, 3x page load speed
 🔶 Healthcare SaaS: as a senior .net developer, HIPAA-compliant rebuild, -40% manual admin work ⚙️ TECH STACK C#, .NET, .NET Core, .NET Framework, .NET MAUI, ASP.NET, React, Angular, Vue.js, Node.js, JavaScript, TypeScript, Python, PHP, Laravel, WordPress, HTML5, CSS 3, jQuery, Bootstrap, MySQL, SQL Server, Git, Azure, AWS, Docker, Software Architecture & Design, Agile Software Development, Desktop Application development 💼 EVERY PROJECT AS A FULL STACK DEVELOPER INCLUDES ▪️ Clean, well-documented C# and .NET code with automated testing
 ▪️ Direct communication, just a senior C# Developer / .NET Developer working on your project 
▪️ Ongoing support after launch as your long-term Full Stack Developer and .NET Developer partner 🏭 INDUSTRIES Fintech · Healthcare · E-commerce · Logistics · SaaS · Real Estate · EdTech 🔎 ALSO EXPERIENCED AS react developer · python developer · java developer · blockchain developer · mobile app developer · wordpress developer · full-stack web developer · python full stack developer · wordpress full stack · full stack developer react · c# .net developer · senior fullstack developer · .net full stack developer · senior .net developer · .net core developer · c developer · cs cart developer · qnap integration · c# wpf · c# angular · c# unity · javascript fullstack · fullstack web developer · full stake developer · c# game developer · full-stack development Each project covers a real client engagement, twice over: react developer dashboard + rebuild; python developer API + script; java developer module + fix; blockchain developer audit + integration; mobile app developer release + update; wordpress developer site + migration; full-stack web developer scope; python full stack developer work; wordpress full stack rebuild; full stack developer react integration; c# .net developer contract; senior fullstack developer judgment; .net full stack developer discipline; senior .net developer oversight; .net core developer debugging; c developer fixes; cs cart developer migrations; qnap integration fixes; c# wpf builds; c# angular dashboards; c# unity prototypes; javascript fullstack proofs of concept; fullstack web developer delivery; full stake developer projects; c# game developer credits; full-stack development results. 🚀 LOOKING FOR A RELIABLE FULL STACK DEVELOPER OR .NET DEVELOPER? 👉 Hire a proven .NET Developer, C# Developer and Full Stack Developer. 📅 Last updated: 07.07.2026

Hey there! I’m Oleksandr, a Senior Full Stack Developer focused on building SaaS platforms, marketplaces, and business applications with React, Next.js, and Node.js. Most of my work is centered around products with complex workflows, payments, dashboards, role-based systems, and scalable backend architecture. I work closely with startups and growing teams to take products from early planning stages to stable production systems used by real customers. I’m comfortable handling both frontend and backend development, improving existing codebases, and building new features with long-term scalability in mind. Some of the platforms I’ve worked on include property management systems, booking marketplaces, operations dashboards, eCommerce platforms, and subscription-based products. 🚀 What I usually work on ✅ SaaS platforms and internal business systems ✅ Marketplace products with multi-role workflows ✅ Admin dashboards and operations tools ✅ Payments, subscriptions, and billing systems ✅ Booking and scheduling platforms ✅ API integrations and third-party services ✅ React Native companion apps ✅ Performance optimization and scaling ⚙️ Tech Stack Frontend: React, Next.js, TypeScript, Redux Backend: Node.js, Express.js, REST APIs Database: PostgreSQL, MongoDB Mobile: React Native, Firebase Infrastructure: Docker, AWS, CI/CD I care about writing maintainable code, keeping communication clear, and building products that are stable long-term, not just quick MVPs. I’m also comfortable joining existing teams, working inside mature codebases, and helping improve architecture and development workflows when needed. If you’re building a SaaS product, marketplace, or internal platform and need a developer who can take ownership of features from planning to production, feel free to reach out.

📢 Available for new projects 📢 I'm a Senior Java Developer with more than 10 years of commercial experience building stable, scalable, and secure backend systems. I specialize in Spring Boot microservices and cloud-native architecture — and I've shipped production systems in Fintech, EdTech, Healthcare, Retail, Hospitality, etc. My core strength is backend architecture: clean APIs, event-driven systems, and services that scale. I also work across the full stack development when needed — React on the frontend, Node.js for integrations, and AWS for deployment and infrastructure. What I bring to your project: - Production-grade Spring Boot microservices and REST APIs - Cloud infrastructure on AWS with Docker and CI/CD pipelines - Full-stack capability: Java backend + React frontend - Relational and NoSQL databases: PostgreSQL, MySQL, MongoDB - Clean, maintainable code with TDD and Agile workflows I've worked on SaaS platforms, enterprise systems, and MVPs — from initial architecture through to deployment. Go-To Stack: Java (Spring Boot, Spring Cloud, Hibernate) · React · Node.js · AWS · Docker · PostgreSQL · MongoDB · Jenkins · GitFlow Ready to start - just drop me a message and we will start working!

🦾 AI-powered solutions. OpenAI integrations. Machine learning capabilities. Business automation. 🧩 Requirements call required. 🛑 No small fixes projects – sorry, guys. I’m an AI Developer and Open AI developer with 13+ years of experience in SaaS products, automation systems, backend platforms, and business tools. My work combines practical AI Integration, scalable architecture, Python developer expertise, JavaScript, and strong product thinking. As an AI Developer, I help clients build internal tools, dashboards, chatbots, AI Langchain workflows, data platforms, web applications, and automation systems. I also work as a Python Django developer when projects need secure APIs, admin panels, user roles, CRM connections, database logic, and stable backend architecture. My stack includes Python, Django, React, JavaScript, REST APIs, PostgreSQL, Docker, OpenAI, Claude, LangChain, vector databases, Zapier, Airtable, n8n, make com, Slack, Google Workspace, and third-party API connections. 💼 Why Work With Me? I don’t just write code — I build systems that solve real business problems. As an AI Developer and Agentic AI Developer, I focus on clean workflows, reliable outputs, automation logic, and product usability. For AI Integration, I connect models with your real data, users, tools, and business processes. This includes AI API Integration, Airtable Integration, chatbots, copilots, document processing, customer support automation, reporting systems, knowledge bases, and smart assistants connected to CRMs, databases, files, and APIs. As a Python developer, I build scalable backend systems with clear structure, secure permissions, optimized databases, background jobs, and clean admin logic. I also support Python developer web scraping, data processing, automation scripts, API integrations, reporting workflows, and ML-related pipelines. On the frontend side, I use JavaScript to build dashboards, admin portals, SaaS interfaces, internal tools, analytics screens, and API-driven product flows that are simple for real users. 💻 Development Expertise AI Developer services: smart assistants, workflow agents, SaaS tools, AI Developer zapier workflows, document analysis, recommendation logic, and business copilots. AI Integration Specialist work: OpenAI, Claude, vector search, Airtable, CRMs, internal databases, n8n, make com, Slack, Stripe, and custom APIs. Python developer work: backend logic, automation, data pipelines, scraping, reporting, API services, background workers, integrations, and analytics. Python Django developer work: SaaS backends, admin panels, authentication, permissions, dashboards, REST APIs, PostgreSQL, Celery, Redis, and secure architecture. JavaScript: React interfaces, dynamic web apps, dashboards, interactive workflows, API-driven screens, and modern frontend development. Machine Learning: NLP, LLM workflows, predictive analytics, AI Machine Learning features, recommendations, classification logic, and business intelligence. 🧠 Use Cases I Can Build AI Developer Langchain projects for SaaS startups, agencies, internal teams, marketplaces, fintech, real estate, operations, and e-commerce. AI Integration for customer support, sales, operations, research, reporting, content workflows, document automation, and internal knowledge systems. Python developer geospatial solutions, Python Full stack platforms, Python AI developer tools, data scientist workflows, web scraping systems, and API Integration pipelines. Full stack developer support for web developer tasks, backend architecture, frontend delivery, automation, dashboards, and production-ready product development. 🔧 How I Approach Projects First, I clarify your goals, process, users, data, integrations, and business priorities. Then I design a practical architecture and build step by step, with attention to reliability, security, performance, and future scaling. For AI Integration, I focus on prompt quality, context structure, data sources, fallback logic, logging, testing, and human review. A strong AI Integration is not just a model call; it is a complete workflow that fits your business. I can also join projects at different stages: early MVP planning, rebuilding legacy workflows, improving existing AI tools, or scaling a working platform. My focus is always on practical delivery, clear communication, clean code, and measurable business value. I’m comfortable working with founders, agencies, product teams, and non-technical clients who need a reliable technical partner, not just a coder. I can help define the MVP scope, choose the right stack, estimate the effort, and then build the product step by step with demos, feedback loops, and stable deployment. If you need a reliable AI Developer who can combine AI Integration, Python developer expertise, JavaScript, Machine Learning, web developer experience, and full-cycle delivery, I can help you build and launch a product that works.

I’m a Senior Full Stack Developer and Software Architect with 13+ years of experience building scalable web applications using .NET, ASP.NET Core, Angular, C#, TypeScript, SQL Server, Azure, and modern cloud technologies. I specialize in full stack development with ASP.NET Core and Angular, developing enterprise-grade SaaS platforms, business applications, CRM systems, ERP systems, dashboards, REST APIs, and cloud-native solutions. My core stack includes: • .NET / .NET Core / .NET 6 / .NET 7 / .NET 8 / .NET 9 • ASP.NET Core • C# Development • Angular 12 / Angular 13 / Angular 14 / Angular 15 / Angular 16 / Angular 17 / Angular 18 / Angular 19 • TypeScript / JavaScript • Full Stack Development • Web API / REST API Development • Entity Framework Core • SQL Server / PostgreSQL / MySQL • Azure Cloud / Azure App Services / Azure DevOps • Microservices Architecture • Docker / Kubernetes • CI/CD Pipelines • SignalR • Clean Architecture • Domain-Driven Design (DDD) • Software Architecture • SaaS Development • Enterprise Application Development • Performance Optimization • API Integration • Authentication & Authorization • JWT / OAuth • Redis / Caching • Agile / Scrum As a Full Stack .NET Developer and Angular Developer, I help businesses build fast, secure, maintainable, and scalable applications with modern UI/UX and robust backend architecture. I have experience leading development teams, designing scalable .NET architectures, modernizing legacy ASP.NET applications, and building Angular frontends integrated with ASP.NET Core APIs. I can help with: - Full Stack .NET & Angular Development - ASP.NET Core Web Applications -Angular SPA Development -SaaS Product Development -Enterprise Software Development -REST API Development -Cloud Migration & Azure Solutions -Legacy System Modernization -Team Leadership & Code Review -Software Architecture Consulting -Performance Optimization -AI-assisted Development Workflows I focus on clean code, scalable architecture, fast delivery, and long-term collaboration. If you need a Senior .NET Developer, ASP.NET Core Developer, Angular Developer, or Full Stack Engineer who understands both business and technology - let’s connect.

Enterprise teams hire me when the React codebase needs to be architected right from the start or rescued from years of shortcuts. I have led frontend teams, built annotation systems for medical imaging from scratch, and delivered two Upwork contracts over $40K each with 5-star reviews. $80K+ earned on Upwork, 100% JSS, Top Rated Plus. What I've built: - Digital Pathology Slide Viewer: Technical Lead on a medical imaging platform for pathologists. Architected the entire annotation system from scratch using OpenSeadragon, including custom polygon clipping algorithms, real-time collaborative annotations via Websockets for concurrent users, and virtualized rendering handling hundreds of annotations simultaneously without performance degradation. Led a team of 2 frontend developers. 1.5 years, team of 5-8. Stack: React 19, TypeScript, NestJS, Redux Toolkit, PostgreSQL, Redis, Docker, GCP. - Media Intelligence Platform: built the entire frontend from scratch for a content aggregation and analytics system pulling from YouTube, Reddit, and web. Real-time dashboards with AG Grid Enterprise and AG Charts Enterprise, Cypress and Jest testing infrastructure, Webpack and Next.js optimization for reduced bundle sizes and faster builds. 1.5 years, team of 4-8. Stack: Next.js, React, TypeScript, NestJS, Websockets, Firebase, PostgreSQL, GCP, OpenAI API. - AI NLP SaaS Platform: led React 16 to React 18 migration for an enterprise NLP system deployed across AWS, GCP, and Azure. Built Survey Service as a standalone Next.js microservice from scratch. Backend contributions in FastAPI and Python. 1 year, team of 5-8. - Multi-Chain Crypto Wallet: Node.js microservices with Fastify and Express, AWS infrastructure via Terraform (EC2, RDS, Redis, S3, CloudWatch), Redis caching and DB indexing for response time optimization. 1 year, team of 10-12. How I work: Architecture documentation before code. Every feature has unit tests and E2E coverage before shipping. When I join a team I establish coding standards, patterns, and review processes, not just deliver features in isolation. Async updates every 2-3 days without being asked. I operate with the full backing of Meduzzen's senior engineering team. Every commit I ship is peer-reviewed by our internal technical leads before deployment. If I am unavailable, your sprints do not stop: a fully briefed Meduzzen engineer provides immediate coverage. One point of contact, zero single-point-of-failure risk. Core stack: React · Next.js · TypeScript · NestJS · Node.js · Redux Toolkit · PostgreSQL · Redis · Docker · AWS · GCP · Websockets · FastAPI · Python · Prisma · Terraform · GitHub Actions. If you need a senior React and Next.js engineer who can own the frontend architecture and contribute to backend systems, send me the brief. I reply within 4 hours.

👋 Need a Front end Developer React who can take ownership of your product and deliver polished, production-ready experiences? I'm a Top Rated Front end Developer React with 15+ years of commercial experience building SaaS platforms, dashboards, customer portals, and modern web applications. With $200K+ earned, 5,300+ hours worked, 31 successful projects delivered, and a 100% Job Success Score, I focus on creating scalable solutions that combine excellent user experience with maintainable architecture. As a React Full Stack Developer, I've helped clients across 15+ countries transform ideas into successful products and scalable platforms. I've contributed to applications ranging from startup MVPs to enterprise solutions serving more than 5 million end-users worldwide. I've built mobile applications used by millions, SaaS products, and streaming platforms delivering real-time video and audio experiences across multiple markets. As a React Full Stack Developer and Full Stack Developer React Node.js, I contribute across the product lifecycle—from frontend architecture and user experience to backend integrations and feature delivery. Having delivered 30+ projects, my experience as a Full Stack Developer React Node.js allows me to support complex business requirements while building reliable systems designed for growth. 🏆 Why Clients Work With Me Top Rated with 100% Job Success 15+ years of commercial development experience $200K+ earned on Upwork 5,300+ hours worked 31 successful projects delivered Products serving 5M+ end-users Clients across 15+ countries Product ownership Scalable solutions Reliable delivery As a React Full Stack Developer, I focus on delivering practical solutions that balance technical excellence with real business objectives. 🚀 Services 📌 Front End Development As a Front end Developer React Node.js, I build responsive, high-performance applications using React, Next.js, TypeScript, and modern frontend practices. Dashboards & Admin Panels Customer Portals Internal Tools Responsive Web Applications Reusable UI Systems Frontend Architecture & Refactoring 📌 Full Stack Product Development As a React Full Stack Developer and Full Stack Developer React Node.js, I work with growing teams to build SaaS products, MVPs, and business applications. SaaS Platforms MVP Development Feature Development Product Modernization Technical Discovery End-to-End Implementation 📌 Backend Integrations As a Full Stack Developer React and Full Stack Developer React Node.js, I integrate backend services supporting business workflows. REST API GraphQL Authentication & Authorization Payment Integrations Third-Party Services 📌 Product Growth As a Full Stack Developer React, I support products beyond launch through performance improvements, architecture enhancements, and ongoing development. 🔧 Technologies React • Next.js • TypeScript • JavaScript • Node.js • Redux • Tailwind CSS • REST API • Supabase • Firebase • PostgreSQL • Docker • Stripe • AWS Throughout my career, I've delivered 31 successful projects for startups and established businesses across 15+ countries. The products I've contributed to now serve more than 5 million users worldwide, helping companies launch faster and scale with confidence. As a React Full Stack Developer and Full Stack Developer React Node.js, I build applications using clean architecture, reusable code patterns, and development practices designed to support long-term business growth. 💼 Selected Experience 🏥 Healthcare Platform Worked on healthcare applications focused on improving operational workflows and user experience. As a Front end Developer React, I developed responsive interfaces, integrated APIs, optimized user journeys, and delivered features supporting medical staff and end users. 🚚 Cargo & Logistics Platform As a React Full Stack Developer and Full Stack Developer React Node.js, I built dashboards, shipment management interfaces, workflow solutions, and integrations supporting logistics operations. 👥 Recruitment & Hiring Platform I developed candidate management more than 150 dashboards, search and filtering systems, workflow features, and integrations supporting recruitment. 📌 Additional Expertise As a Front end Developer React, I collaborate with founders, product managers, and stakeholders to transform business requirements into intuitive user experiences and scalable technical solutions. I have experience working with existing codebases as well as building products from the ground up. My background as a Full Stack Developer React Node.js includes implementing secure authentication flows, integrating payment systems, optimizing application performance, and supporting products through multiple stages of growth. 📌 Industries Healthcare • Logistics • Recruitment • Booking Platforms • E-commerce As a Full Stack Developer React Node.js, I enjoy partnering with ambitious teams building products designed to scale. let's connect.

I build and engineer operational systems that remove friction, prevent cost, and keep products stable under real-world scale. At Melio - A fintech platform processing billions in B2B payments and later acquired by Xero for $3B, I worked inside the core product systems handling real financial risk, where architectural decisions directly impact transaction reliability, cost, and scale. At Rightway - A healthcare platform valued at $1.1B serving 500,000+ members across 850+ clients, I built product features within the care navigation system that influenced how people make healthcare decisions in real time, under strict reliability and performance constraints. I’ve also worked on a third high-growth product in a different vertical that reached unicorn-level scale. Details are available in conversation. This work wasn’t surface-level engineering. I was inside production systems, shipping under pressure, where failures cost money, users, and trust. What I do I don’t “build features.” I design systems that hold up when usage scales, requirements change, and edge cases start to dominate. • SaaS platforms, fintech systems, healthcare products, marketplaces Built from scratch or stabilized at scale, always focused on long-term structure, not short-term delivery. • System architecture Backend design that reduces dependency, removes bottlenecks, and prevents future operational breakdowns before they happen. • AI integration in production systems OpenAI, Gemini, and custom pipelines integrated into real workflows, not demo environments. • Long-term product engineering Deep involvement in product logic and business constraints. Average engagement spans 12+ months. Tech stack Backend: Laravel (primary), Node.js, Python, Go Frontend: React, Next.js, Vue, TypeScript Mobile: React Native AI: OpenAI API, Google Gemini, LangChain Databases: PostgreSQL, MySQL, MongoDB, Redis Infra: AWS, GCP, Docker, Kubernetes, CI/CD pipelines Testing: PHPUnit, Jest, Cypress, Playwright How I work I operate in EU timezone with overlap into US hours. Communication is structured and predictable: daily async updates, weekly alignment. I adapt to your workflow tools (Jira, Linear, GitHub, Slack) instead of forcing mine onto yours. Estimates are conservative and realistic. If something takes 3 weeks, it is 3 weeks "Not a sales number". When needed, I scale delivery through a vetted network of senior engineers I’ve worked with long-term, without compromising system integrity. "When the Systems Work, Everything Works"

Most "AI developers" can wire ChatGPT to a database. I build agent systems that survive in production — orchestrators with retries, state management, observability, and cost control. 6+ years as a Software Engineer, now full-time System Engineer building AI-driven SaaS at Mplus (DE), available for select Upwork projects. I'm Martin — Top Rated, 100% JSS, 5★ across all closed contracts. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ WHAT I ACTUALLY SHIP → Production AI agents that don't fall over Stateful agents with retries, tool routing, error recovery, observability, and cost control — not a demo that breaks on the second user. → Custom orchestration when frameworks aren't enough LangGraph and Claude MCP where they fit. Custom architectures when your workflow doesn't fit a framework. I design the agent system — I don't just bolt one together. → Claude & OpenAI integrations done seriously Anthropic Claude with Tools and MCP, OpenAI Assistants & Agents SDK, function calling, structured outputs, streaming, hybrid model routing for cost/latency trade-offs. → Full-stack delivery around the agent Python for the AI layer, Node/TypeScript for APIs and web. Postgres, pgvector, queues, webhooks. The agent isn't the product — the system around it is. I build both. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ CURRENT WORK (gives you a sense of what I do day-to-day) System Engineer at Mplus (DE) — building an AI-driven SaaS for residential energy efficiency analysis: B2C assessment tools plus a B2B contractor marketplace. Real users, real production. Past: R&D monitoring system for a Tel Aviv pharmaceutical client. High-traffic B2C platform with 1.2M+ users at Enkonix (AWS, message queues, cross-team integrations). ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ MY STACK AI Layer: Anthropic Claude (Tools, MCP), OpenAI Assistants & Agents SDK, LangChain, LangGraph, custom orchestration Backend: Python (primary), Node.js, TypeScript, FastAPI, Express Data: PostgreSQL, pgvector, Redis, MongoDB, Supabase Infra: AWS, Vercel, Docker, queues, webhooks, observability Web: React, Next.js (when the agent needs a UI around it) ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ HOW I WORK Day 1-2: Discovery call. I map your agent's workflow, edge cases, and failure modes BEFORE writing code. Week 1: First working agent loop in staging — you run real inputs against it. Ongoing: Async updates, weekly demo, observability dashboard so you see what the agent is doing. Handoff: Clean repo, README, evals, deployment docs, runbook for common failures. ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ NOT A FIT IF YOU NEED: ✗ "Build me a ChatGPT clone" — that's a wrapper, not an agent ✗ Pure prompt engineering with no system behind it ✗ Trading bots, gambling, or crypto-trading AI ✗ The cheapest bid — I'm not it ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ If you've hit reliability walls with n8n + GPT, or you're past the prototype stage and need a real system — send me the brief. I'll come back with a scoped architecture plan, not a generic pitch. — Martin