Hire the Best Web Application Developers in California

Hi, my name is Andres. I am a full stack developer with over 15 years of experience building web applications from the ground up. I specialize in data driven AngularJS and Angular applications with NodeJS backends. If you are passionate about your vision, let's talk, I will be happy to help make it a reality.

𝗧𝗼𝗽 𝗥𝗮𝘁𝗲𝗱 𝗣𝗹𝘂𝘀 | 𝟭𝟬𝟬% 𝗝𝗼𝗯 𝗦𝘂𝗰𝗰𝗲𝘀𝘀 | 𝟭𝟯+ 𝗬𝗲𝗮𝗿𝘀 | 𝟴,𝟬𝟬𝟬+ 𝗨𝗽𝘄𝗼𝗿𝗸 𝗛𝗼𝘂𝗿𝘀 | $𝟮𝟬𝟬𝗞+ 𝗘𝗮𝗿𝗻𝗲𝗱 | If your project demands more than a developer who just writes code, if you need someone who can architect it, own it, and ship it to production, that's exactly what I do. - I specialize in designing and building scalable .NET/Azure-powered platforms for SaaS companies, healthcare organizations, and enterprises across the US. Whether you're starting from scratch, modernizing a legacy system, or scaling a platform that's hitting its limits, I've done it, repeatedly, for real businesses. PMP Certified | Fast communicaton | 53 completed projects on Upwork. WHAT I BUILD FOR YOU ────────────────────────────────────────── ✦ SaaS Platforms - Multi-tenant, subscription-based, cloud-native applications on .NET Core and Azure, designed to scale from 10 users to 100,000 ✦ Healthcare Systems - HIPAA-aware EHR/EMR platforms, HL7/FHIR integrations, and clinical workflow applications built to compliance standards ✦ AI-Powered Applications - OpenAI/LLM integrations, intelligent document processing, and AI-enhanced workflows wired into your existing .NET stack ✦ Enterprise APIs & Integrations - REST APIs, microservices, and third-party integrations (Stripe, QuickBooks, Twilio, CRMs, ERPs) built for reliability ✦ Cloud Architecture & DevOps - Azure and AWS infrastructure, CI/CD pipelines, Docker/Kubernetes, and full infrastructure automation ✦ Legacy Modernization - Turning outdated codebases into maintainable, cloud-ready platforms without breaking what works ────────────────────────────────────────── 𝗧𝗘𝗖𝗛 𝗦𝗧𝗔𝗖𝗞 Backend: - C# · .NET Core / .NET 8+ · ASP.NET Core · ASP.NET MVC · Web API · WCF · ADO.NET · EF Core · LINQ to SQL · Razor Pages · Blazor · SignalR · WebSockets · Microservices · REST APIs · SOAP APIs · Multi-tenant architecture Frontend: - Angular · React · Next.js · TypeScript · JavaScript · HTML5 · CSS3 · Bootstrap · Blazor UI Cloud & DevOps: - Azure (App Services · Functions · AKS · Service Bus · Key Vault · Logic Apps · Azure SQL · Storage) - AWS (EC2 · Lambda · RDS · S3 · SES) - CI/CD · Azure DevOps · GitHub Actions · Docker · Kubernetes · Infrastructure as Code · IIS Deployments Database: - SQL Server · PostgreSQL · SQLite · Cosmos DB · MongoDB · Entity Framework / EF Core · Stored Procedures · Functions · Views · Query Optimization · High-Performance / High-Volume Systems Integrations & APIs: - Stripe · PayPal · Twilio · SendGrid · OAuth / OAuth 2.0 · CRM/ERP Integrations · Payment Gateways · Third-party REST/SOAP APIs · HL7 · FHIR · Microservice Integrations Version Control & Tools: - Git · GitHub · GitLab · Bitbucket · Azure Repos (TFS) · SourceTree · TortoiseGit · Postman · Jira · Asana · ClickUp · Visual Studio Reporting & Legacy Systems: - Crystal Reports · Custom Reporting Solutions · Legacy System Maintenance & Modernization AI & Automation: - OpenAI · ChatGPT APIs · LLM Integrations · AI-driven Automation Workflows ────────────────────────────────────────── HOW I WORK - I stay involved from architecture through deployment,,, writing clean, documented, production-ready code and communicating clearly at every step. I manage scope, timelines, and stakeholder expectations as well as I manage code. - I work as a Senior Engineer, Solution Architect, Technical Lead, or long-term fractional CTO,,, depending on what your project actually needs. ────────────────────────────────────────── LET'S TALK Send me a message with your project scope — what you're building, where you're stuck, or what you need to scale. I respond within a few hours and will tell you honestly if I'm the right fit.

Hi there! 👋 I’m a Full Stack Systems and App Developer with over 7 years of experience crafting high-performance applications, scalable backend systems, and intuitive user interfaces for startups, enterprises, and everything in between. Whether you're building a lightning-fast single-page application, a robust backend API, or a cross-platform mobile app, I bring together deep technical expertise, architectural thinking, and a relentless commitment to clean, maintainable code. 💡 What I Do As a full stack developer, I thrive at the intersection of backend architecture, frontend design, and system-level logic. I build entire systems from the ground up—or jump into existing codebases and elevate them to the next level. ✅ Web Apps (Admin panels, dashboards, marketplaces, SaaS platforms) ✅ Mobile Apps (React Native, Flutter, or native Android/iOS) ✅ System Integrations (APIs, microservices, third-party tools) ✅ Custom APIs (REST & GraphQL) ✅ Authentication Systems (JWT, OAuth2, SSO, multi-factor auth) ✅ Real-time Features (WebSockets, Push Notifications, Live Updates) ✅ DevOps (CI/CD pipelines, Docker, NGINX, cloud deployments) ✅ Security & Performance Optimization ⚙️ Tech Stack I Master Frontend #React, Next.js, Vue.js #TailwindCSS, Bootstrap, Material UI #Redux, Zustand, SWR, React Query #TypeScript, JavaScript (ES6+) Backend #Node.js, Express, NestJS #Python (FastAPI, Flask), PHP (Laravel) #Java (Spring Boot), Go (Gin/Fiber) #RESTful API & GraphQL #WebSockets, Redis, RabbitMQ Databases #MongoDB, PostgreSQL, MySQL #Firebase, Supabase #Redis for caching #ElasticSearch for search optimization Mobile #React Native, Flutter #Expo, Firebase Auth & Realtime DB #Native modules & integrations #Offline storage & synchronization DevOps / Tools #Docker, NGINX, PM2 #GitHub Actions, GitLab CI/CD, Jenkins #AWS (EC2, S3, Lambda), Vercel, Netlify #Postman, Swagger, Insomnia #Unit, integration & E2E testing (Jest, Cypress, Mocha) 🚀 Why Work With Me? 🔹 Systematic Problem Solver – I break down complex problems and solve them with modular, scalable solutions. 🔹 Pixel-Perfect Delivery – I translate Figma/AdobeXD/Sketch designs into highly responsive, fluid UIs. 🔹 Scalable Thinking – Every system I build is designed with future growth, performance, and maintainability in mind. 🔹 Transparent Communication – I value clear communication, regular updates, and real-time collaboration. 🔹 Fast & Reliable – Tight deadline? No problem. I deliver production-ready solutions with zero compromise on quality. 🔧 What I’ve Built Before 📈 A B2B SaaS platform for sales analytics used by Fortune 500 teams 💊 A full-featured EHR (Electronic Health Records) system for clinics 🛒 E-commerce mobile apps with real-time inventory syncing 🔐 Secure document management platform with role-based access 📱 Social networking app with live chat, feeds, and stories 💼 Admin dashboards for multi-tenant enterprise CRMs ⭐ Client Testimonials “One of the best developers I’ve worked with. Built our entire app from zero to MVP in under 3 weeks. Clean code and proactive communication.” — Startup Founder, HealthTech (USA) “Takes full ownership of systems and brings solutions, not problems. If you need a long-term dev, hire this guy now.” — CTO, SaaS Product (Germany) 📩 Let’s Build Together Whether you're looking to build from scratch, need an extra brain on your dev team, or want to scale your app to the next level—I’m ready to help. 📆 Send me a message and let’s talk about your project! I respond quickly and am happy to hop on a call or review your idea.

I am a highly motivated, dedicated professional web application developer, designer and engineer, with over 15 years of real-world experience developing mission-critical projects, for a diverse and wide range of systems. Main areas of focus being Full Stack Web Development, PHP, Python, React, Node MySQL, REST, API. I've built very strong programming skills and a talent for identifying and implementing innovative technology solutions that align with client objectives to deliver solutions that encompass the full spectrum of existing and future project needs. These are some of the tools I wield to help businesses accomplish their technological goals : CORE COMPETENCIES ✪ . Web Development ✪ . Back-End Development ✪ . Full-Stack Development ✪ . Ecommerce Development ✪ . Web Design ✪ . Custom Coding / Programming TECHNICAL SKILLS ✪ . Languages: PHP, Perl, HTML,JavaScript, CSS, SQL, C#, JQuery ✪ . Frameworks: Symfony, CakePHP, CodeIgniter, Bootstrap ✪ . Technologies: SAML, XML, OpenToken, Amazon Web Services, Google Cloud Platform, JSON, REST, SEO, CMS, SOAP, AJAX, API ✪ . Databases: MySQL, MSSQL, SQL, MS Access

𝗦𝗲𝗻𝗶𝗼𝗿 𝗙𝘂𝗹𝗹-𝗦𝘁𝗮𝗰𝗸 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿 | 𝗡𝗼𝗱𝗲.𝗷𝘀 | 𝗡𝗲𝘅𝘁.𝗷𝘀 | 𝗥𝗲𝗮𝗰𝘁.𝗷𝘀 | 𝗣𝗼𝘀𝘁𝗴𝗿𝗲𝗦𝗤𝗟 | 𝗔𝗪𝗦 | 𝗔𝗣𝗜 𝗜𝗻𝘁𝗶𝗴𝗿𝗮𝘁𝗶𝗼𝗻 | 𝗠𝗘𝗥𝗡 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿 I am a Senior Full Stack Developer with 10+ years of experience building modern, scalable and high-performance web applications from frontend to backend. I specialize in React.js, Next.js, Node.js, and PostgreSQL, delivering complete end-to-end solutions with clean architecture, responsive design, and seamless API integrations. My focus is on building full stack products that work beautifully on the frontend and scale reliably on the backend. I have worked on healthcare, fintech, logistics and SaaS platforms, handling everything from pixel-perfect UI to database design, REST API development, and cloud deployment. 𝗣𝗿𝗼𝗳𝗲𝘀𝘀𝗶𝗼𝗻𝗮𝗹 𝗘𝘅𝗽𝗲𝗿𝗶𝗲𝗻𝗰𝗲 𝟭- 𝗦𝗲𝗻𝗶𝗼𝗿 𝗙𝘂𝗹𝗹-𝗦𝘁𝗮𝗰𝗸 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿 | 𝗙𝗶𝗻𝘁𝗲𝗰𝗵 𝗣𝗹𝗮𝘁𝗳𝗼𝗿𝗺 - Built fintech platform with virtual cards, wallet flows, and real-time dashboards - Developed REST APIs, database architecture, and responsive frontend UI - Managed complex app states including loading, errors, modals, and empty states Skills: React.js, Next.js, Node.js, PostgreSQL, REST API, TypeScript, Material UI 𝟮- 𝗦𝗲𝗻𝗶𝗼𝗿 𝗙𝘂𝗹𝗹-𝗦𝘁𝗮𝗰𝗸 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿 | 𝗟𝗼𝗴𝗶𝘀𝘁𝗶𝗰𝘀 𝗣𝗹𝗮𝘁𝗳𝗼𝗿𝗺 - Built logistics platform with shipment tracking, booking flows, and operational dashboards - Designed scalable REST APIs and backend business logic - Delivered responsive, maintainable full-stack architecture Skills: React.js, Next.js, Node.js, Express.js, PostgreSQL, AWS, TypeScript 𝟯- 𝗙𝘂𝗹𝗹-𝗦𝘁𝗮𝗰𝗸 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗲𝗿 | 𝗛𝗲𝗮𝗹𝘁𝗵𝗰𝗮𝗿𝗲 𝗣𝗹𝗮𝘁𝗳𝗼𝗿𝗺 - Developed healthcare web app with frontend + backend ownership - Built REST APIs, database management, and responsive UI architecture - Worked long-term with US client on ongoing feature development Skills: React.js, Node.js, PostgreSQL, REST API, TypeScript, AWS 𝗞𝗲𝘆 𝗦𝗸𝗶𝗹𝗹𝘀 & 𝗧𝗲𝗰𝗵𝗻𝗼𝗹𝗼𝗴𝗶𝗲𝘀 𝗙𝗿𝗼𝗻𝘁𝗲𝗻𝗱 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗺𝗲𝗻𝘁 - React.js, Next.js, JavaScript (ES6+), TypeScript - Redux, State Management, Component-Based Architecture 𝗨𝗜 & 𝗦𝘁𝘆𝗹𝗶𝗻𝗴 - Tailwind CSS, Material UI, Responsive Web Design - Pixel-Perfect UI, Cross-Device Development 𝗕𝗮𝗰𝗸𝗲𝗻𝗱 𝗗𝗲𝘃𝗲𝗹𝗼𝗽𝗺𝗲𝗻𝘁 - Node.js, Express.js, Nest.js, Python, Flask - REST API, GraphQL, WebSockets, Microservices 𝗗𝗮𝘁𝗮𝗯𝗮𝘀𝗲𝘀 - PostgreSQL, MongoDB, MySQL, Redis - Database Design, Query Optimization, Data Modeling 𝗖𝗹𝗼𝘂𝗱 & 𝗗𝗲𝘃𝗢𝗽𝘀 - AWS, Docker, CI/CD - Vercel, Heroku, Azure, Firebase 𝗧𝗼𝗼𝗹𝘀 & 𝗖𝗼𝗹𝗹𝗮𝗯𝗼𝗿𝗮𝘁𝗶𝗼𝗻 - GitHub, Jira, Trello, Agile/Scrum - Figma, Cross-Functional Team Collaboration 𝗙𝗹𝗲𝘅𝗶𝗯𝗹𝗲 𝗖𝗼𝗹𝗹𝗮𝗯𝗼𝗿𝗮𝘁𝗶𝗼𝗻 I work across multiple time zones and adapt to full-time, part-time, or milestone-based projects, ensuring clear communication and on-time delivery. 𝗪𝗵𝘆 𝗪𝗼𝗿𝗸 𝗪𝗶𝘁𝗵 𝗠𝗲? ✅ 10+ years of Full-Stack experience across frontend and backend ✅ End-to-end ownership, from UI design to database and cloud deployment ✅ Clean, scalable, and maintainable code across the entire stack ✅ Experience across fintech, healthcare, logistics and SaaS ✅ Reliable, client-focused developer committed to on-time delivery 𝗞𝗲𝘆𝘄𝗼𝗿𝗱𝘀 Full Stack Developer, MERN Developer, React Developer, Next.js Developer, Node.js Developer, JavaScript Developer, TypeScript Developer, REST API Developer, PostgreSQL Developer, AWS Developer, Python Developer, Backend Developer, Frontend Developer, Web Application Developer, SaaS Developer, Fintech Developer, Healthcare Platform Developer, Logistics Platform Developer, Responsive Web Design, API Integration, Cloud Deployment

I provide consulting and software development for Google Workspace (Sheets, Forms, Apps Script), Desktop apps, and applications that run in the browser. Let's Chat! I prefer video calls so we can better communicate and quickly get to what you are looking for. Select Projects Custom quoting application in Google Sheets and Apps Script for multiple home remodel companies (the construction and wholesale building materials industries) - Resulted in quotes being sent out in hours instead of days (their salespeople loved it), allowing them to get their quotes to leads ahead of their competitors and closing more sales. Custom Google Sheet for an HVAC company - Created a template Google Sheet for their business specific quoting process and automated it with formulas and scripts, cutting down work and allowing them to send quotes out faster compared to their previous paper method. QR code inventory manager in Google Sheets and Apps Script - Created for a client to manage their inventory list with QR codes, and using a web application that runs on their phone, scan QR codes and manage their inventory right from their phone. Used by a regional soda distributor, amongst others. I have worked with entrepreneurs and small businesses and I was the lead architect and programmer for the SaaS product engage-ai.co. What I can do for you * Create custom quote, project management, and sales order software in Google Sheets or as a custom web application to fit your business processes * Make your Google Sheets more automated, making your team more productive * Move your existing desktop software to a cloud based custom web application to fit your unique business processes * Connect your business' various software to help your team keep on top of customer and project changes