⭐ Full Stack Developer | .NET | PHP | MERN | AI | Mobile App Developer | Flutter Developer | iOS & Android Specialist I am a Full Stack Developer, Mobile App Developer, and Flutter Developer trusted by Google, Samsung, BMW, and LG. I help startups and enterprises build high-performance mobile apps and scalable web platforms using Flutter, .NET, PHP, MERN, Android, iOS, and AI technologies. If you're looking for a dependable Flutter App Developer, iOS Developer, Android Developer, Full Stack Developer, or MERN Developer, I can take your project from concept → UI/UX → development → backend → deployment → scaling. 🚀 Why Clients Hire Me Expert Full Stack Developer for web & mobile apps Senior Flutter Developer for cross-platform mobile apps Experienced iOS Developer & Android Developer for native apps Strong .NET Developer, PHP Developer, and MERN Developer AI-Driven App Development (chatbots, automation, ML features) Delivered 50+ successful apps for global brands Clear communication, fast delivery, and long-term support Clients frequently choose me when searching for: Full Stack Developer, Flutter Developer, Mobile App Developer, iOS Developer, Android Developer, .NET Developer, PHP Developer, MERN Developer, AI Developer. 💼 What I Do 📱 Mobile App Development Flutter App Development (iOS + Android in one codebase) iOS App Development (Swift, Xcode) Android App Development (Kotlin, Java) Firebase, REST API & cloud integrations UI/UX implementation, app optimization & bug fixing Full-cycle Mobile App Developer services from idea to rollout 🌐 Full Stack Web Development MERN Stack Development (MongoDB, Express, React, Node.js) .NET Web Development (ASP.NET, .NET Core) PHP / Laravel Development Custom REST API development Admin panels, dashboards, CRMs, web portals, SaaS platforms Backend architecture, authentication, cloud deployment 🤖 AI & Automation AI-powered mobile & web apps AI chatbot development Intelligent automation systems AI API integration (NLP, vision, recommendations, workflows) 🔧 Tech Stack Mobile Flutter, Dart Kotlin, Java Swift, Xcode Web / Backend MERN Stack (MongoDB, Express, React, Node.js) .NET, ASP.NET Core, C# PHP, Laravel JavaScript, jQuery Firebase, SQL, MySQL REST APIs, Cloud Integrations ⭐ Industry Expertise Taxi Web & App Developer Rideshare Web & App Developer Food Delivery Web & App Developer Grocery Delivery Web & App Developer E-commerce Web & App Developer Marketplace Web & App Developer On-Demand Services Web & App Developer Fitness Web & App Developer Health & Telemedicine Web & App Developer EdTech Web & App Developer Learning Management (LMS) Web & App Developer Job Portal Web & App Developer Social Media Web & App Developer FinTech Web & App Developer Digital Wallet Web & App Developer Crypto Wallet Web & App Developer Inventory Management Web & App Developer Real Estate Web & App Developer Vehicle Rental Web & App Developer Travel & Hotel Booking Web & App Developer Auction & Bidding Web & App Developer Subscription Web & App Developer SaaS Web & App Developer Productivity Web & App Developer Event Management Web & App Developer Dating Web & App Developer Parenting Web & App Developer Mental Health Web & App Developer Meditation & Mindfulness Web & App Developer Language Learning Web & App Developer News & Magazine Web & App Developer Podcast & Audio Streaming Web & App Developer 🎯 Ready to Build Your App or Platform? Click Invite to Job and let’s bring your idea to life — mobile, web, or AI.

Full Stack Developer | AI Agents, LLM Apps & Data Science | Next.js | Node | Python | GoLang I build production AI applications, data pipelines, and full-stack SaaS platforms for startups and enterprise teams. Recent work: a SaaS platform with 5 live AI automation modules (65 planned across a 24-week rollout) and a HIPAA-compliant medical records platform where every data access is logged and defensible. 10+ years shipping code, the last two focused on AI-accelerated development with Claude Code, Codex, Cursor, and whatever ships next: multi-agent systems and LLM integrations that actually run in production. What I do AI engineering: Claude, OpenAI, and Gemini integrations, multi-agent orchestration with LangGraph, RAG pipelines, evaluation harnesses, and production-grade LLM features that hold up beyond the demo. I recently built a Claude-powered proposal generator and an AI report analysis pipeline, both live in production. Data science & ML: Data pipelines, ETL, feature engineering, model integration, and analytics tooling. Pandas, NumPy, scikit-learn, and the glue code that gets models into production. Full-stack development: React / Next.js, Node.js, Python / Django, FastAPI, PostgreSQL, React Native. Clean APIs, sensible architecture, code that other engineers can maintain. Shipped platforms include (HIPAA-compliant EMR: role-based access control, PHI encryption, audit trail logging built to HIPAA Security Rule standards). AI-accelerated workflows: Daily use of Claude Code, Codex, and Cursor with custom configs, MCP server integrations, and agentic dev loops that meaningfully cut delivery time on real client work. Comfortable picking up new AI tooling as it emerges. Cloud & infrastructure: AWS, GCP, Azure, Docker, CI/CD. Built for the load you actually have, not the load a slide deck says you'll have. Industries: SaaS, healthcare (HL7/FHIR/DICOM/HIPAA), fintech, ecommerce (including Shopify and Amazon SP-API), and AI-native startups. Technology Stack: React, Next.js, Node.js, TypeScript, Python, Django, FastAPI, PostgreSQL, Redis, Docker, AWS, GCP, LangGraph, Pandas, scikit-learn, Claude Code, Codex, Cursor, OpenAI / Anthropic / Gemini APIs, React Native. If you're building something AI-heavy, data-driven, or need a senior engineer who can own delivery end-to-end, send over the details and I'll tell you honestly whether I'm the right person for it.

I'm a health data engineer specializing in wearable and patient-generated data interoperability built on open standards. I'm a contributing member of the JupyterHealth software team (UC Berkeley / UCSF), where I serve as the primary developer and architect of the patient-generated data sync and Open Wearables integration work for the JupyterHealth Exchange. I build the tooling that gets data from devices like Oura, Whoop, Garmin, and Apple Health flowing into clinical-grade FHIR-based exchanges and in the standard Open mHealth format. My work covers: - Wearable data pipelines using Open Wearables and Open mHealth (IEEE 1752.1) - Patient-facing sync apps with consent, authorization, and reliable data delivery - FHIR interoperability for clinical and OMH for research systems - Health data infrastructure (Django, Fly(dot)io, AWS, CI/CD, OAuth2/OIDC, SAML) - SMART on FHIR integration (built an Epic integration through to production readiness) - AI-accelerated specification and development for health data systems I work in the open-source health ecosystem, not as a generalist learning on your dime. Clients keep ownership of standards-based, interoperable work with no proprietary lock-in.

Top 1% Expert-Vetted Freelancer on UpWork ✅ Hi 👋 I’m Gabe. I’m an AI-native senior product engineer who uses modern AI tools to ship production-grade software faster — without sacrificing architecture, quality, or long-term maintainability. I have 10+ years of experience building and scaling apps for Fortune 500 companies and startups, especially in high-stakes systems where timelines are tight or codebases already exist. My stack includes Cursor, Replit, OpenClaw, and LLMs — used where they actually make sense to move faster and reduce bugs. Everything I ship is grounded in clean architecture and production-ready code. What I Bring to the Table 🧠 AI-Native Development – Faster iteration without sacrificing quality 📱 Mobile & Full-Stack Expertise – React Native (iOS & Android), TypeScript, React, Next.js, Firebase, Vercel, Railway 🚀 MVPs & Prototypes – From idea → working product quickly 🛠 Fixing & Scaling Existing Apps – Notifications, performance, migrations, stability 📞 Clear Communication – Realistic estimates, proactive updates, no surprises Why Work With Me? ✅ Top 1% on Upwork (Expert-Vetted) ✅ Fortune 500 + high-traffic production experience ✅ Strong ownership and long-term thinking ✅ Trusted to solve hard problems, not just ship features Testimonials ⭐ “Gabe was incredible. He went above and beyond.” ⭐ “Great estimates, great communication, and consistently high-quality work.” If you're building something that matters, send me a message describing the problem. I'll let you know within 24 hours if I'm the right fit.

Full-stack and React Native developer who builds web and cross-platform mobile apps, React, Next.js, Node.js, MongoDB · 5-star rated. Need one developer who can build your web app and mobile app without switching teams or losing context? I deliver complete, production-ready products across web and mobile — using React, Next.js, Node.js, MongoDB, and React Native for iOS & Android. Whether it's a SaaS web platform, a cross-platform mobile app, or both running off the same backend — I've got the full stack covered. What I build: ✅ Full-Stack Web Apps — React / Next.js + Node.js / Express backend ✅ Cross-Platform Mobile Apps — React Native (iOS & Android) ✅ REST API & GraphQL API — shared backend for web + mobile ✅ MongoDB & PostgreSQL Database Design ✅ Authentication — JWT, OAuth 2.0, NextAuth.js, Firebase Auth ✅ SaaS Dashboards, Admin Panels & Client Portals ✅ Push Notifications, Offline Support & App Store Deployment ✅ Responsive UI — Tailwind CSS, Material UI, Shadcn How I work: Clear communication, realistic timelines, and clean code your team can build on. You'll always know where the project stands — no surprises at delivery. Tech stack: JavaScript · TypeScript · React.js · Next.js · React Native · Node.js · Express.js · MongoDB · PostgreSQL · REST API · GraphQL · Firebase · Tailwind CSS · Expo · Git · Vercel · AWS Building a web platform, mobile app, or both? Send me your project brief and I'll respond promptly.

If the problem involves AI touching real decisions—and getting it right matters—I’m usually a good fit. I routinely deliver what would take most teams a week in a single day. As one former Upwork client put it: “Got a week’s worth of work done in less than an hour due to Jonathan’s expertise. Would work with him again, no question.” That speed comes from deep domain expertise and fluency with modern AI tooling, which I use as a force multiplier—not a shortcut. I move quickly because I know exactly what to build, what not to build, and how to avoid rework through systematic testing. Most of my work sits in environments where systems influence money, risk, or operations, and where errors are expensive. The goal is not experimentation or novelty. It is building systems that work the first time, explain their decisions, and remain reliable under scrutiny. I led the design and implementation of an AI-driven small-business credit platform for a publicly traded lender (~$40M+ annual revenue). The system automated the majority of application decisions by combining structured financial data, document understanding, and retrieval-augmented analysis with tool-enabled research. Within a controlled environment, the system could query internal data, perform constrained external searches, and assemble a 30-point underwriting profile aligned with senior credit-analyst reasoning. Crucially, the system enforced confidence thresholds and escalation logic. Only the most complex 10–15% of applications were routed to expert underwriters, allowing human effort to concentrate where judgment actually added value. Manual review fell sharply without increasing risk. Security was treated as a first-order constraint. All PII was isolated within private network boundaries, with encrypted storage and tightly scoped access. Even large-language-model interactions—including external research—were routed through secured infrastructure so sensitive data never left controlled environments. Most engagements begin with a short diagnostic phase. I’m direct about whether I’m needed at all—and when I’m not, I say so. Clients often use a less expensive developer for execution once the critical architectural and risk decisions are made. That discipline is part of the job. Selected Systems I’ve Built At Finally, a $100M Series-B payroll company, I designed and shipped a production payroll platform in roughly six weeks, making early architectural decisions that prevented later rewrites and operational debt. In academic publishing, I helped build and stabilize Refine.ink, an AI-driven peer-review platform used by faculty at leading U.S. universities, where rigor, explainability, and predictable behavior were non-negotiable. As Refine.ink’s co-founder put it: “Jonathan combines deep technical ability with unusually strong judgment. He consistently identified the right problems to solve and built systems we could trust in production.” — Ben Golub, Co-Founder, Refine.ink; former Professor of Economics and Computer Science at Harvard; current Professor of Economics at Northwestern University I’ve also built agentic and multimodal systems that execute real workflows: voice-driven legal intake systems that conduct structured interviews and route qualified matters directly into case management; and computer-vision pipelines where I fine-tuned custom object-detection models to classify industrial weld defects—often only a few pixels wide—achieving ~95% accuracy with a lightweight human-review loop. I’m typically brought in when teams need rapid progress without mistakes—when systems have to move fast and still hold up in production. I work quickly because I’m an expert at what I do and deeply fluent in AI tooling, which allows me to compress timelines without cutting corners.

I'm proficient with many frameworks, tech skills, and programming languages including React, NodeJs, HTML/CSS/JS, Firebase, Flutter, Python, Unity, WPF, ThreeJs, databases like PSQL, MySQL, and others. I've worked for a few years now here and on Freelancer, and been involved in developing and working on many interesting projects like websites, and apps & games for several platforms. I have the experience and breadth of skills to tackle many software development projects from things I am familiar with (Unity games & apps, web pages - React is my fav frontend, Flutter apps), to even things I may not have direct experience with at the moment. I learn quick, listen well, and always try to deliver good quality results. If it's software development related, I can probably do it.

Java and Spring Framework expert with over 7 years of experience in the software engineering. If you're looking for a skilled Software Engineer who can help you build fast, scalable, and high-performance applications, then look no further. Let's work together and bring your project to life. Skills: - Programming Languages: Go, Java, Kotlin, Swift, React - Technologies: Gin, Viper, Serverless, SpringBoot, Kafka, Akka, Splunk, ELK - Database: DynamoDB, Couchbase, MS SQL, MySQL, Spring Data, DB2 - Source Control, Dev Ops: AWS, Github, Gitlab, Docker, Kubernetes, Helm, OpenShift/RHEL, Jira, qTest, NewRelic, Datadog 𝐖𝐇𝐀𝐓 𝐒𝐄𝐓𝐒 𝐌𝐄 𝐀𝐏𝐀𝐑𝐓: I have 7 years of Industry experience, working in companies having customers in the millions & building and maintaining applications responsible for well over a thousand requests per second. I have built synchronous and asynchronous systems - Dozens of REST APIs and message queues. Reach out today, and together we'll create digital experiences that stand out in the crowd.

Hello! I'm Stephen Carruthers and passionate about building websites and designing user interfaces to bring software to life. However, my true passion lies not only in solving problems, but providing the best possible solutions through cutting-edge technology. This mentality has enabled me to gain invaluable experiences skills, such as strategic thinking, effective communication, and comprehensive project development. I've played pivotal roles in designing, developing, and delivering exceptional desktop and web-based products. With extensive full stack experience, I specialize in technologies like PHP, JavaScript, TypeScript, WordPress, HubSpot, C#, and ASP.NET. I've extensive experience with concepts such as relational and document store databases, REST APIs, cloud engineering (AWS), CI/CD, and much more. If you're looking for a developer who merely closes tickets, there are plenty to choose from. However, if you want a top-tier problem solver and talented developer who can drive your projects to success, you have found the right person. Let's chat and see how I can help.

⭐ Expert AI Engineer & Full-Stack Developer | LLMs, RAG, AI Agents | React.js, Node.js Specialist ⭐ ⭐ Top Rated with 100% Job Success | 10+ Years Experience ⭐ ⭐ Full Stack Web & Mobile Development | AI Integration | Cloud Solutions (AWS, Azure, Google Cloud) ⭐ With over 10 years of experience in software development, I specialize in building intelligent, scalable applications that transform businesses. My expertise spans cutting-edge AI technologies, modern full-stack development, and enterprise-grade solutions for healthcare, eCommerce, and SaaS platforms. Key Skills & Expertise: 📌 AI & Machine Learning Solutions: AI Agents, LLM, N8N models, ChatGPT, Claude, OpenAI API Integrations, AI Assistant, AI appointment booking 📌 Front-End Development: React.js, Next.js, Vue.js, Nuxt.js, Tailwind CSS, Bootstrap, HTML5, CSS3 📌 Back-End Development: Node.js, Express.js, PHP, Laravel, Ruby on Rails, Python Django 📌 CMS & eCommerce: WordPress, Shopify, WooCommerce, Webflow 📌 Database Management: MySQL, MongoDB, PostgreSQL, Firebase 📌 Mobile Development: React Native, Flutter 📌 API & SaaS: RESTful API, Custom SaaS Apps, Payment Gateways (Stripe, Paypal, Authorize.net) 📌 SEO & Speed Optimization: Core Web Vitals, Page Speed, Mobile Optimization Why Work With Me: ✓ Top Rated with 100% Job Success Score, Proven track record of delivering exceptional results ✓ 10+ Years of Expertise – Successfully delivered complex projects across multiple industries ✓ Domain Specialist – Deep experience in healthcare (HIPAA compliance), eCommerce, fintech, SAAS and AI applications ✓ AI Innovation Leader – Reduced operational costs by up to 70% through intelligent automation ✓ Clear Communication – Regular meetings, updates, video calls, and collaborative problem-solving ✓ Long-Term Partnership Focus – I build lasting relationships, not just complete projects ✓ End-to-End Ownership – Independent, reliable developer who can own features while keeping you informed ✓ Results-Driven Approach – Focus on ROI, scalability, and long-term business success My Services: ✓ AI-Powered Applications (LLMs, RAG, AI Agents, Chatbots) ✓ Full Stack Web Development (React, Node.js, Laravel, .NET, Ruby on Rails) ✓ Mobile App Development (React Native, iOS, Android) ✓ eCommerce Solutions (Shopify, CS-Cart, OpenCart, Custom Stores) ✓ SaaS Product Development (Multi-tenant Architecture, Subscription Management) ✓ Backend API Development (RESTful, GraphQL, Microservices) ✓ Cloud Solutions (AWS, Azure, Google Cloud Administration) ✓ Database Design & Optimization (MySQL, PostgreSQL, MongoDB) ✓ DevOps & CI/CD (Docker, Kubernetes, Automated Deployments) I believe great software comes from understanding your business goals, not just writing code. I start every project by listening to your needs, asking the right questions, and proposing solutions that scale with your growth. Whether it's a quick call to discuss architecture or regular standups to track progress, I'm committed to transparent, collaborative development that delivers measurable results. Specialization Areas: AI Integration | LLMs | RAG Systems | AI Agents | React.js | Node.js | Next.js | Angular | Vue.js | TypeScript | Laravel | .NET | Ruby on Rails | React Native | Django | MVP | MVC Ready to Get Started? Click the "Hire Now" button or send me an invitation to chat. I look forward to hearing from you and discussing how we can bring your vision to life.