I enjoy programming Android applications, i like to program on Flutter so i can deliver for iOS too I enjoy working with firebase and all their tools. I also worked as Informatics Professional on Audi, Germany Apps programmed on native Android: ·Tracker of the Argentinian Stock Market (Back-end on the cloud, on Node.js) ·Educational app Apps programmed on flutter : ·Second version of the Educational app about economics ·SpaceX app with notifications for launches and Augmented Reality(on development) ·Social network for Sharing Recipes with live streaming and videochat Other side projects: ·Virtual Office for Virtual Reality(Oculus) on C#(on development) ·A flight simulator with an airplane cabin (Microcontrollers on C + computer software on C#) ·Websites (I can Fullstack on Javascript ( Node.js Express.js jQuery Bootstrap ) ) I can also speak German and Spanish. Therefore I can offer to translate your projects so they cover a way broader audience (Spanish covers the markets of Latin America, and with German we can cover the markets of the richest european countries)

Hi, I’m Vishal- Full-Stack Developer I help startups and growing businesses build secure, scalable, and production-ready web applications using modern JavaScript frameworks and cloud-native architecture. With years of professional experience, I specialize in full-stack SaaS development, real-time systems, and backend engineering. I focus on writing clean, maintainable code and delivering solutions that scale smoothly as your product grows. ## What I Can Help You With - Full-stack web applications (Node.js, React, Next.js) - Secure REST APIs & backend services - SaaS platforms & MVP development - Real-time features (calls, chat, live updates) - Payment gateway integration (Stripe, PayPal) - Authentication & authorization (JWT, RBAC) - AWS serverless & cloud integrations ## Tech Stack - Backend: Node.js, NestJS, Express - Frontend: React, Next.js - Databases: MongoDB, PostgreSQL - Cloud: AWS (Lambda, S3, SQS, SNS) - Practices: Clean Architecture, SOLID, DDD ## Professional Highlights - Built real-time communication modules using Vonage & PubNub - Integrated Stripe & PayPal for secure payment workflows - Developed serverless AWS solutions for scalable processing - Created a custom Yeoman CLI to accelerate NestJS project setup - Designed a dynamic authorization system using ORY & Kong ## How I Work - Clear communication & regular updates - Strong ownership and accountability - Focus on long-term maintainability, not quick hacks - On-time delivery with production-ready quality Let’s build something reliable and scalable. Send me a message and let’s discuss your project.

A Software Engineer with more than 3 years of experience in software architecture, design & implementation for Web applications. Technical and management expertise in financial, trading systems, distributed and payment systems using Python, Javascript, AWS, Docker, Kubernetes, Deployment Automation and several related technologies. Well versed in design and implementation of large and complex projects particularly in Backend, cloud infrastructure and CI/CDs ✅ Python Django, Django REST, FastAPI, OpenAI ✅ CI/CD Gitlab CI, Google Cloud Build ✅ AWS VPC, ECS, Beanstalk, AWS Batch, Route53, S3, IAM, ECR, ALB, Cloudfront, RDS, Glue, MQ, SES ✅ Javascript React, React Native, Expo, Redux, Chakra UI ✅ GCP Google Kubernetes Engine, SQL ✅ Infrastructure As Code Kubernetes ✅ Others Docker, FFMPEG, OpenFaaS, Render.com, GitLab Dedicated Setup, Stripe, Git, PubNub, Sendgrid, Postmark, Google APIs

Hi! I’m a Senior Full-Stack Engineer and Fractional CTO with over 10 years of experience building and scaling web applications, leading teams, and delivering high-quality software. I’ve worked across startups and established companies, building production systems end-to-end, from architecture to clean and reliable code. Since I’m new on Upwork, I’m offering discounted rates for my first clients. You get senior engineering quality at an accessible rate while I build my Upwork profile. What I can help you with: • Full-Stack Development – TypeScript – React / Next.js – Node.js – Serverless applications – API design and development • Backend Engineering – Authentication and permissions – Payments and billing systems – Microservices – Real-time features (WebSockets) – Database design and optimization • Cloud / DevOps – AWS (Lambda, S3, EC2, RDS, CloudFront) – CI/CD pipelines – Infrastructure as code – Monitoring and logging setups • CTO & Architecture Consulting – Product and technical roadmaps – System design and architecture – Code reviews and audits – Security best practices Why clients choose me: • Reliable, predictable delivery • Clear, consistent communication • Clean, scalable, well-structured code • Product thinking, not just coding • Calm, professional, and easy to work with Special offer for my first Upwork clients: A free 10-minute code or architecture review so you can see my approach before making a decision. Feel free to message me. I respond quickly.

Fullstack PHP/JavaScript developer specialized in WooCommerce & WordPress development. Plugin development: - Extensive experience in developing custom plugins for WooCommerce, including solutions for: shipping, payment gateways, order tracking and marketplace. - REST API custom endpoints for integration with external systems. - Products search integration with ElasticSearch, Algolia and Meilisearch. Theme development: - Extending the WooCommerce Cart and Checkout blocks with additional functionality. - Development of custom Gutenberg blocks. - Optimizations for top scores in Lighthouse and ensuring excellent performance across all web performance metrics Scaling and optimizations: - Troubleshooting slow sites using tools like Query Monitor, WP CLI Doctor etc to pinpoint slow database queries. - Database tuning, indexing tables for better query performance. - WordPress object cache with Redis for caching. - Proficient with caching plugins such as W3 Total Cache (W3TC) and WP-Optimize to achieve faster load times and greater site stability under high traffic. - Implementing background processing using ActionScheduler library.

I’m a Senior Native Android Engineer with 10+ years of experience building, scaling, and optimizing Android applications used by thousands to millions of users. I specialize in: • Building Android apps from scratch (architecture → production → scaling) • Taking over legacy codebases and modernizing them • Improving performance, stability, and user experience • Architecting clean, testable, and maintainable systems I write production-grade code that is built to last. ⸻ 🧠 What You Can Expect Working With Me ✔ Clean Architecture (MVVM, MVI, Modularization) ✔ Kotlin-first development ✔ Coroutines & Flow ✔ Testable code (Unit + Integration tests) ✔ CI/CD friendly structure ✔ Performance optimization & memory management ✔ Pixel-perfect UI aligned with Material Design I don’t just “make apps work.” I build apps that scale, perform, and are easy to extend. ⸻ 🔧 Technical Expertise Core Android • Kotlin, Android SDK, Gradle, Android Studio • Jetpack (LiveData, ViewModel, Navigation, Room) • Coroutines, Flow, RxJava • Dependency Injection (Dagger / Hilt) Architecture & Scale • Modularized architecture • Clean Code, SOLID principles • CI/CD workflows • Large-scale app optimization APIs & Backend Integration • REST & GraphQL APIs • Retrofit, OkHttp • AWS (Cognito, AppSync, Amplify, S3, DynamoDB) • Firebase (Auth, Analytics, FCM, Storage) Advanced Integrations • Payments (Stripe, PayPal, Google Billing) • Google Maps, Geofencing, GPS • Real-time chat (XMPP, PubNub, QuickBlox) • Push notifications • Social media integrations Platforms • Android TV & Amazon Fire TV ⸻ 💼 How I Work I communicate clearly, meet deadlines, and take ownership of outcomes — not just tasks. Whether you need: • A full Android app built from idea to launch • A senior engineer to audit and refactor your codebase • Performance and crash optimization • Feature expansion in an existing app I’m here to help. I’m comfortable working across time zones and collaborating with distributed teams. ⸻ If you’re building something meaningful and want a senior engineer who treats your product like their own — let’s talk.

Senior React & React Native Engineer | Scalable Web & Mobile Solutions Profile Summary I help businesses turn ideas into scalable, high-performance web and mobile applications. With 7+ years of experience, I specialize in React, React Native, Next.js, and Node.js, delivering production-ready solutions for startups and product-based companies in the USA and UK markets. I don’t just write code, I build reliable, maintainable, and user-focused products. From requirement gathering and architecture design to deployment and post-launch optimization, I manage features end-to-end with strong ownership and attention to detail. I’m comfortable working in Agile environments, collaborating directly with product owners, designers, and distributed teams across time zones. My focus is always on performance, scalability, clean architecture, and business impact. What I Can Help You With ✔ Cross-platform Mobile Apps (React Native) ✔ Modern Web Applications (React / Next.js) ✔ API Development (Node.js / NestJS / REST / GraphQL) ✔ App Store & Play Store Deployment ✔ Firebase & Real-time Features ✔ Performance Optimization & Refactoring ✔ Long-term Product Development Support Technical Expertise Mobile: React Native, Android, iOS, Flutter Frontend: React, Next.js, Angular, Redux, TanStack Query Backend: Node.js, NestJS, PHP, Laravel, Meteor APIs: RESTful APIs, GraphQL Cloud & DevOps: Firebase, Firestore, Cloud Functions, OneSignal, Twilio, SendGrid, PubNub, Sentry, Docker, GitHub Actions Databases: MySQL, PostgreSQL, MongoDB, SQLite Tools: Jira, Linear, Basecamp Version Control: Git, SVN If you're looking for a reliable senior engineer who understands both technology and business needs. let's build something great together.

Mobile Apps Expert | 10+ Years of Experience Android • iOS • Flutter • React Native • Kotlin Multiplatform • AI Agentic Tools • Cloud Apps I’m a Senior Mobile Developer with 10+ years of experience delivering fast, stable, and scalable mobile applications for startups, enterprises, and global brands. I specialize in building high-quality Android, iOS, and Cross-Platform apps using Flutter, RN, and KMP, all with clean architecture and production-ready code. 💡 Whether you need a new app, want to fix or optimize an existing one, or plan to scale with cloud + AI-powered features, I can help you deliver a polished product—on time and with zero hassle. 📱 Mobile App Expertise 🔹 Android SDK/NDK – Deep hands-on experience with Java, Kotlin and Compose 🍎 iOS Development – Expert in Objective-C, Swift and Swift UI 🧩 Cross-Platform Mastery – Flutter, React Native, and Kotlin Multiplatform (KMP) 🧱 Focus on performance, scalability, and native-like UX across platforms 🧠 Architecture & Code Quality 🧭 Strong in MVP, MVVM, MVI and Clean Architecture 🧩 Experienced in modular app design, ensuring scalability & maintainability 🧹 Advocates clean code, SOLID principles, and test-driven development (TDD) 🌐 Real-Time & Networking ⚡ Built real-time apps using Socket Programming and XMPP (chat, live updates) 🔗 Expert in REST, GraphQL, Retrofit, and RxJava for API integration 🗄️ Database & Data Handling 💾 Proficient in SQL (MySQL, PostgreSQL) and NoSQL (MongoDB, Firestore, CouchDB) 🧮 Skilled in data modeling, indexing, and query optimization for performance 🔌 Integrations & SDKs 🌍 Integrated Google APIs (Maps, Location, Directions, Calendar) & Facebook SDK/Graph API 🔥 Experienced with Firebase Suite – Auth, Firestore, Notifications, Crashlytics, Analytics 💳 Implemented multiple payment gateways – Stripe, PayPal, Braintree, Razorpay 📊 Used PubNub, ElasticSearch, and analytics tools for live data tracking 🧰 Version Control & CI/CD 🧠 Strong with Git, GitHub, GitLab, and Bitbucket ⚙️ Automated builds & deployments via Jenkins, GitHub Actions, Bitrise, Fastlane 🪙 Blockchain & Emerging Tech 🔗 Hands-on with Corda, Hyperledger Fabric/Indy 🌐 Exposure to Web3, NFTs, and Solidity Smart Contracts for Apps 🤖 AI-Accelerated App Development (Agentic AI Tools) ⚡ Faster, Smarter Development – Harnessing Agentic AI tools like Qoder, Gemini, Claude, and OpenAI Coder to accelerate app delivery. 🧠 AI-Assisted Architecture & Coding – Designing scalable architectures and generating clean, maintainable code through AI-driven suggestions. 🧩 Context-Aware Coding Agents – Utilizing autonomous AI agents that refactor code, suggest optimizations, and enhance quality in real time. 🔄 Rapid Prototyping & Iteration – Turning ideas into functional prototypes faster with AI-driven UI generation and auto-code completion. 🧮 Smart Debugging & QA – Detecting bugs and writing test cases automatically using AI-assisted workflows. 💬 Natural Language Development – Writing and reviewing code through conversational prompts using Claude, Gemini, or OpenAI Coders. 🚀 Productivity Multiplied – Delivering production-ready apps faster, with higher quality and efficiency through AI + human expertise. 🎨 UI/UX & Collaboration 🎯 Worked closely with designers using Figma, Adobe XD, Sketch ✨ Built responsive UIs, custom animations, and smooth navigation flows 🤝 Soft Skills & Leadership 🧩 Excellent communicator & agile team player 🧑‍💻 Strong in client communication, requirement gathering, and scrum process 🧭 Proven leader – mentoring juniors & delivering complex apps on time

Your online business presence is super important in the modern world. New technologies emerge every month, websites get hacked or become slow and not compatible with modern devices. That is where I come in. My full stack skills will make your website fast, reliable and easy to expand in the future. I provide multiple services that include: - designing and implementing websites, ranging from simple marketing sites to complex web-apps - improving performance and modernizing legacy applications - hardening your site's security using the latest standards - deploying to production, with SEO optimized, HTTPS enabled - integrating payments, including PayPal and Stripe - automating as much as possible My favourite tech stack is Django REST Framework in the backend and Angular in the frontend, but I am technology-agnostic and can quickly pick up any tech on the go. Here is a list of what I've used in the past: -Python 2/3, Django 2-5, Celery, Channels, Strawberry GraphQL, DRF -Angular 2-21, RxJS, ngrx, signals -React, Next.js, Vue 3, Nuxt.js -Node.js, NestJS, Express, FastAPI -PostCSS, LESS, SCSS, Bootstrap, Material Design -PostgreSQL, MySQL, MariaDB, Amazon RDS, SQLite -Redis, queues, caching -Git, Github, Gitlab, Bitbucket -JIRA, Trello, Asana, Slack -HTML5, CSS3 -Ubuntu, Nginx, Docker, Jenkins -Scrum, Agile, TDD -Cypress, Karma, Chai, Jasmine -AWS, Azure, Digital Ocean Why 'modern' in my title? Frameworks and other dependencies change every day. New versions contain important security fixes, performance improvements and new features. I spend many hours following the latest news, conferences, checking changelogs and testing different versions for compatibility to make sure that your app benefits from those changes. Testimonials: "Fast, communicates great and reliable. The kind of guy I like doing business with and I'm picky." "Tomasz did a very good job working on an existing angular project. He got everything set up independently, migrated everything to a recent angular version and was able to start coding in no time. " "Tomasz presented good knowledge of Python and Django. His communication was very clear and professional, and he was able to dive right into some complicated code and significantly improve its performance. He is a reliable and skilled contractor who I would recommend."

✅ 100% Job Success Rate ✅ 10+ Years of Experience 🏆 Team Technostacks Services & Expertise 🏆 We offer end-to-end digital product development with a strong focus on performance, usability, and scalability. ✅ AI/ML‑centric applications (including LLMs, Generative AI, and Agentic AI) ✅ Customize Web & Mobile App Development ✅ SaaS Product Development & Cloud Integration ✅ IoT applications with Wi‑Fi and BLE integrations ✅ Product Engineering & Modernization ✅ Cloud & DevOps (AWS, Azure, GCP) ✅ AR/VR applications ⚙️ Team Technostacks Developed and Managing Apps ⚙️ ✅ 100K+ Downloads | 50K+ Active users / Day | 50K+ USD earnings per year | 12% to 20% Increment in efficiency ✅ High traffic | 3rd Party SDK code customization and integration | Take over project from another team ✅ Multiple projects from same enterprise | Funded Startups to Enterprise | Worked with global team 🏅 Team Technostacks Awards, Accreditations & Partnerships 🏅 ✅ AWS Select Tier Services Partners | GCP | Zoho Authorized Partner | ISO/IEC 27001:2013 Certified Company ✅ W.E. Global Employees’ Choice Award 2024 | NASSCOM Member | PubNub Integration Partner ✅ Top Developers 2019 on Clutch | Top Mobile Application Development Company 2019 on Clutch ✅ Top IoT Developers 2019 on Clutch | Top VR & AR Developers 2019 on Clutch 🌍 Team Technostacks Work & Impact ✅ Industries We Served: Healthcare | Life Science | Fintech | Logistics | Education | Industrial ✅ Globally recognized by CNN | TechCrunch | Business Insider | Shark Tank | NBC | W.E. Global Employees ✅ We have delivered 100+ successful projects globally from AI-driven healthcare systems to enterprise SaaS platforms and IoT-Powered industrial solutions. At Technostacks, we foster a collaborative and client-focused culture, driven by innovation, precision, and accountability. We believe in building long-term partnerships and delivering digital products that make a real impact. Let’s collaborate 🤝 to build your next successful digital solution.