Are you looking for a reliable, skilled, and forward-thinking developer to ship a production-ready web platform and Android & iOS applications end to end? I design and deliver full-stack development (React/Next.js + Node.js) and cross-platform apps (React Native/Flutter). I focus on clean architecture, secure applications, and scalable solutions from API development to App Store deployment with a sharp eye for responsive UI/UX design. What I DeliverFull-Stack Web: 1-Frontend: React.js, Next.js (SSR/SSG), Tailwind CSS for responsive UI/UX 2-Backend: Node.js, Express, REST & GraphQL APIs, WebSockets 3-Databases: PostgreSQL, MongoDB, Supabase, Firebase 4-Auth & Security: OAuth, JWT, RBAC/SSO, best-practice API hardening 5-Ops: CI/CD implementation (GitHub Actions, Docker), testing, logging, monitoring 6-Cloud Solutions: AWS/GCP/Azure for deployments, storage, and secret management Mobile App Development (Android & iOS): 1-React Native Developer (CLI & Expo) and Flutter Expert for cross-platform apps 2-Native integrations: camera, geolocation, deep links, background tasks, file uploads 3-Push notifications (FCM/APNs), in-app purchases & subscriptions 4-App Store deployment: TestFlight & Play Console, provisioning, signing, release notes 5-Performance & reliability: offline-first (SQLite/Room/WatermelonDB), accessibility Product & Operations 6-Payment integrations: Stripe, PayPal, Razorpay (subscriptions, refunds, webhooks) 7-Analytics/observability: Firebase Analytics, Crashlytics, Sentry, PostHog 8-Scalability: caching, pagination, queues; API versioning and staged rollouts Core Services 9-Full-Stack Development for dashboards, admin panels, data-heavy web apps 10-API Development & third-party integrations (REST/GraphQL, webhooks) Mobile App Development from MVP to App Store/Play Store launch: 1-System hardening: auth, roles/permissions, secure storage, rate limiting 2-Performance tuning and scalable solutions for growing user bases 3-Maintenance & upgrades: dependency hygiene, security patches, long-term support Technical Summary: 1-Frontend: React, Next.js, HTML5/CSS3, Tailwind CSS 2-Backend: Node.js, Express, REST, GraphQL, WebSockets 3-Mobile: React Native, Flutter, Expo; Kotlin/Java (Android), Swift (iOS) 4-Data: PostgreSQL, MongoDB, Supabase, Firebase, SQLite 5-Auth/Security: OAuth, JWT, RBAC, secure sessions & tokens 6-Payments: Stripe, PayPal, Razorpay; in-app purchases/subscriptions 7-DevOps/Cloud: Git, Docker, GitHub Actions, AWS/GCP/Azure 8-QA/Analytics: Jest, Sentry, PostHog, Firebase Analytics & Crashlytics Why Teams Choose Me: 1-Ownership end-to-end: full-stack web + mobile + deployment 2-Predictable delivery: clear milestones, documentation, maintainable code 3-Production mindset: secure applications, robust releases, and codebases teams can extend 4-If you’re building a full-stack platform with mobile apps, need API development with payment integrations, or want a partner who can own delivery from idea to launch, let’s talk.

I build the systems that let growing businesses move faster — multi-tenant SaaS platforms, e-commerce engines serving multiple EU markets, and AI-powered tools that replace manual work with intelligent automation. 8+ years shipping production software. I've led a 10-person engineering team delivering SaaS products for US and EU clients with full SDLC ownership, co-founded a startup (Plan 9 top 20), and now work directly with international clients as a senior engineer. No handoffs, no coordination overhead — one person who owns frontend, backend, AI integrations, and deployment. Here's what I've shipped: → Multi-tenant e-commerce SaaS (React 19 + Node.js + Prisma + PostgreSQL) — Shopify, Amazon, Etsy, eBay integrations, Stripe billing, EasyPost shipping. Deployed on Vercel + Render. → React Native/Expo mobile app (ongoing contract) — Full-stack development within a TypeScript monorepo (Next.js, Hono, Drizzle ORM, Neon PostgreSQL). Shipping multi-phase product features, PostHog A/B experimentation, and deep link navigation flows. → SportsWriters — PostgreSQL performance optimization reducing API response times from 3.5s to under 500ms via ORM-to-raw-SQL migration, maintaining 99.9% uptime across 1M+ daily requests. → AI Integration Suite — RAG document retrieval pipelines, AI voice assistants (Groq Whisper, OpenAI), structured tool-calling chat agents, and embedding-based semantic search. → CareDesk — Hospital management system (Next.js + Supabase) with real-time communication, scheduling, role-based access, and Vercel edge function auth. Pro bono for a non-profit hospital. → Cross-platform mobile apps with Azure Speech-to-Text, real-time transcription (SwiftUI + Kotlin). → E-commerce platform targeting 6 EU markets — Next.js, Prisma, Cloudflare R2, SendCloud logistics. → GoHighLevel CRM build — pipelines, intake forms, calendar booking, automations for an EU expat services company. Core stack: TypeScript, React, Next.js, Node.js, NestJS, PostgreSQL, Prisma, React Native/Expo. Also: OpenAI/LangChain, Azure Cognitive Services, Docker, CI/CD (GitHub Actions), Drizzle ORM, Stripe, Supabase. I also teach Web Development and AI as Visiting Faculty at Beaconhouse National University — which means I can explain what I'm building and why, not just ship code. If your project involves SaaS architecture, e-commerce integrations, mobile apps, or adding AI to an existing product — message me with the details and I'll tell you honestly whether I'm the right fit.

I build AI systems that take the repetitive, manual work off your team's plate. Not chatbots, not advice: working automation that ships on your existing stack, runs on a schedule, and holds up after I've gone. Almost two decades of experience in commercial operations sit behind the builds. I've designed automation that took a cross-border marketplace from zero to six-figure revenue with about 60% less manual overhead, run a forensic audit of 500+ projects that surfaced seven-figure margin leakage at a VC-backed agency, and built a suite of AI operating systems that turn messy processes into income. I work with businesses of every size: solo founders, ecommerce, trades, and professional services, agencies, and VC-backed SaaS teams. Earlier in my career I ran commercial and marketing operations for brands including Google, Meta, Amazon, L'Oreal, IKEA, WPP, and Linklaters. WHAT I BUILD ▶ Multi-agent AI systems that handle repeatable business functions end-to-end (research, qualification, content, decision support) ▶ AI-powered/OCR pipelines for invoice processing, contract extraction, and document workflows ▶ AI-augmented dashboards and BI tooling that turn messy data into leadership-ready insight ▶ Operating systems from scratch with AI baked into the cadences, escalation paths, and governance ▶ Operational rebuilds where AI enhances or replaces the manual middle: audit, scope, replace, embed HOW IT'S GONE ▶ A mid-size construction firm wanted to surface new project leads before anyone else. I built them a tool that took data from five sources, validation and enrichment from a couple more, and presented it back in an easy-to-use dashboard with pre-written scripts and emails for outreach. ▶ A cross-border ecommerce business was drowning in manual finance admin. I built an email-to-P&L pipeline: OCR ingests invoices, an automated flow handles approval, and a live P&L updates in real time. No one types numbers off PDFs any more. ▶ A trend-led service needed to watch multiple data sources daily without anyone reading a thread. I shipped three live workflows: a Reddit scraper feeding structured output into Notion, a daily news digest into Slack against a defined topic set, and a Claude pipeline that reads source material, processes it, and writes back to Notion for repurposing. Zero manual research time. TECH STACK ▶ AI: Claude Code/Cowork/Design/API/Skills, OpenAI Codex/API, custom GPTs, Gemini/API/Nano Banana, Midjourney, Cursor, Perplexity. ▶ Automation & integration: n8n, Make, Zapier, Pabbly, Python, Node.js, Playwright, Twilio ▶ Infrastructure & deployment: Cloudflare Workers, Cloudflare R2, GitHub Actions, Vercel, Supabase (Postgres + RLS), Sanity, REST APIs, webhooks ▶ Frontend & web: Next.js, HTML5, CSS3, Vanilla JavaScript, Tailwind, WordPress, Shopify ▶ Document processing: Custom OCR pipelines, AI-driven extraction, python-docx, DocuSign, Notion API ▶ CRM, sales & payments: HubSpot, Salesforce, Intercom, Stripe, Paddle ▶ Operations & PM: Notion (Advanced Admin Certified), Monday, ClickUp, Asana, Airtable ▶ Data & analytics: SQL, Looker, PostHog, Plausible ▶ Customers and support: Zendesk, Intercom, Crisp, Mailchimp, Brevo ▶ Communication: Slack, Microsoft 365, Google Workspace, Resend, Twilio ▶ Design & collaboration: Figma, Miro, Adobe Suite, Canva ▶ HR, Finance, & people: HiBob, Greenhouse, Quickbooks, Xero ▶ Dev: GitHub, Retool, Vercel I work fast, I communicate clearly, and I don't need managing. If you've got a process held together with spreadsheets and good intentions, I can probably fix it.

I write copy that sells and build the automations that deliver it. Two things I do exceptionally well: Direct response copy: sales pages, email sequences, VSL scripts, webinar funnels, and lead gen content. I've written launches that generated multiple six figures and one seven-figure campaign. I work across coaching, courses, SaaS, and service businesses. Marketing automation: I build workflows in n8n, Make com, and Claude Code + native APIs that connect your CRM, email platform, and ad tools so leads get followed up automatically. I've worked with Engage, Customer io, Brevo, MailerLite, ActiveCampaign, Kit, HubSpot, Keap, Ontraport, Pipedrive, Attio, with PostHog, Google Analytics, Tag Manager, and most major platforms. Recent work includes managing PPC and email automation for a UK home services company (lead segmentation, CRM integration, automated follow-up sequences) and building AI-assisted content production workflows for LinkedIn and newsletter publishing. I build lead magnet platform for a sales coach for LinkedIn prospecting, with leads going into an email autoresponder, contacts updated in the CRM, email marketing and warm-lead nurturing happening using the AnchorCast private podcast strategy. I deliver fast, communicate clearly, and I'm available for both one-off projects and ongoing work. Specialties: Marketing Automations, email sequences, newsletters, sales pages, landing page copy, webinar scripts, VSL scripts, n8n workflows, Make com automations, CRM setup and integration, lead generation funnels, AI-powered content workflows.

I help founders turn rough product ideas into shippable AI, SaaS, web, and mobile products. My edge is full product execution: architecture, UX, full-stack development, AI/API integrations, analytics, payments, CRM automations, and launch funnels. If the scope is messy, I can help turn it into a practical MVP, build plan, or working product. Recent work includes: - AI creator platform with image/video generation, payments, token packs, and production launch hardening - AI companion app funnel analysis using PostHog/RevenueCat-style data to improve activation and subscription paths - AI lead acquisition platform with voice agents, CRM automation, email/SMS follow-up, and webinar funnels - Mobile/dating product work, including private dating-journal UX, App Store packaging, and retention-focused product design Good first projects: - MVP architecture sprint or technical roadmap - React/Next.js, mobile, or SaaS feature repair - AI workflow/API integration - Product analytics and conversion funnel cleanup - Launch-ready landing page, onboarding, payment, or CRM flow Background: U.S. Air Force veteran, Penn State IT graduate, and former software engineer at Lockheed Martin and Vanguard. I communicate clearly, move fast, and care about building products that can actually survive launch.

I design and develop production-grade websites and mobile applications, with a specialization in AI-assisted engineering that delivers enterprise-quality work at unusual speed. Independently, I have built five production applications totaling more than 100,000 lines of code — SaaS platforms, mobile marketplaces, health-tech applications, and an AI operating system for robotics. Every one is shipped, live, and running in production today. My web work is built on Next.js, React, and Tailwind, with a focus on conversion, performance, and design execution that holds up to scrutiny. On mobile, I build cross-platform and native iOS applications that meet App Store standards on first submission. Across both disciplines the standard is the same: a product that performs, not a prototype that demos. I have worked with every significant AI engineering tool since the field opened — beginning with ChatGPT the week it launched in November 2022, and continuing through GPT-4, Claude, Cursor, Claude Code, Windsurf, Bolt, v0, and Devin. I have advised on Claude Code adoption at the enterprise level, and I can identify which tools are worth integrating, which are not, and how to embed them into a team's workflow so the gains are measurable. If you need a website designed, a mobile application developed, or AI capabilities integrated into an existing operation, I can deliver end-to-end, on schedule, and to a standard you can put your name on.

Are you looking for a developer who can ship a production-ready web platform and Android and iOS apps end to end, and also add practical AI features that actually work in production? I build full-stack products using React and Next.js with Node.js, and I develop cross-platform mobile apps with React Native or Flutter. On top of that, I integrate AI into real workflows like internal knowledge bases, support automations, summarization, and smart search. I focus on clean architecture, secure builds, and scalable delivery from API development to live deployment. What I deliver: Full-stack web: 1) Frontend: React.js, Next.js (SSR and SSG), Tailwind CSS for responsive UI 2) Backend: Node.js (Express) and Python (Django), REST and GraphQL APIs, WebSockets 3) Databases: PostgreSQL, MongoDB, Supabase, Firebase 4) Auth and security: OAuth, JWT, RBAC, SSO, API hardening 5) Ops: CI and CD, Docker, testing, logging, monitoring 6) Cloud: AWS, GCP, Azure deployments, storage, secrets Mobile apps (Android and iOS): 1) React Native (CLI and Expo) and Flutter for cross-platform apps 2) Native integrations: camera, geolocation, deep links, background tasks, uploads 3) Push notifications, subscriptions and in app purchases 4) App Store delivery: TestFlight and Play Console, signing, releases 5) Performance and reliability: offline-first storage, accessibility, crash monitoring AI integration for real products: 1) AI chat and copilots for apps and internal tools 2) RAG knowledge bases using your PDFs, docs, and web content, with source citations 3) Document processing pipelines: extraction, cleanup, tagging, and structured outputs 4) Support automation: ticket triage, suggested replies, and handoff to humans 5) Safe AI: guardrails, prompt control, role-based access, and logging 6) Cost and quality controls: token usage tracking, evaluation, and monitoring Product and operations: 1) Payments: Stripe, PayPal, Razorpay, webhooks, refunds, subscriptions 2) Analytics and observability: Sentry, PostHog, Firebase Analytics, Crashlytics 3) Scalability: caching, pagination, queues, API versioning, staged rollouts 4) Maintenance: dependency hygiene, security patches, long-term support Why teams choose me: 1) Ownership end to end: web, mobile, backend, deployment, and integrations 2) Predictable delivery: clear milestones, documentation, maintainable code 3) Production mindset: security, stability, and systems teams can extend 4) Practical AI: AI features tied to real user workflows, not demos If you are building a full-stack platform with mobile apps, want to add AI features like knowledge base chat or document automation, or need a partner who can own delivery from idea to launch, I can help. If you want, I can also give you a shorter version (more punchy, less lists) and a version that is more B2B SaaS focused, so you can A B test which one converts better on Upwork.

Full-Stack Engineer | Rust, Axum, Next.js, TypeScript, PostgreSQL | AWS | Supabase I am a Full-Stack Software Engineer with 6+ years of experience and 3,100+ hours on Upwork, specializing in building scalable web applications, APIs, and backend systems. My primary expertise includes: • Rust & Axum • TypeScript & JavaScript • Next.js & React • Node.js & Express • PostgreSQL • PostHog • REST APIs • AWS,Supabase & DigitalOcean • Python, Django & Flask • Docker • Git & GitHub • Analytics & Product Instrumentation (PostHog) I have worked with startups and product companies to design, build, and deploy production-grade applications. My experience includes developing: • High-performance backend APIs • Authentication & authorization systems • Real-time applications • SaaS platforms • Analytics dashboards • Internal business tools • 3D web applications using Three.js, Babylon.js, and Model Viewer Recent work includes: • Building and maintaining production web applications using Next.js and PostgreSQL • Developing backend services and REST APIs • Migrating applications from monolithic architectures to scalable service-oriented systems • Integrating third-party APIs, analytics, and payment systems • Performance optimization and bug fixing for existing applications What clients can expect: • Clear communication • Fast turnaround • Clean and maintainable code • Reliable delivery • Long-term technical thinking If you need help building, scaling, debugging, or modernizing your application, I would be happy to discuss your project. Let's build something great together.

I'm Sanjay Kumar – a dedicated Software Engineer with over 3 years of hands-on experience in both web and mobile app development. Specializing in React, Next.js, and React Native, I've built scalable and high-performance applications across diverse industries. At AlphaSquad, I tackled challenging projects that honed my React JS expertise, transforming legacy websites into dynamic, single-page applications with advanced performance optimizations. My journey spans several roles where I’ve consistently delivered impactful results—from revamping company websites using Next.js and Tailwind CSS to developing full-stack solutions for global platforms. I excel in leveraging modern tools such as Redux, React Router, TypeScript, and the broader MERN stack to create clean, maintainable code that drives seamless user experiences. Whether optimizing backend processes to drastically reduce latency or integrating third-party APIs for real-time communications, I bring a balance of technical precision and creative problem-solving to every project. Beyond my technical skills, I’m a proactive lifelong learner, committed to staying updated with the latest trends and best practices in development. My strong communication and collaboration skills empower me to thrive in team environments and deliver results that exceed expectations. I’m excited about the opportunity to contribute my expertise on new projects at Upwork and help transform your digital vision into reality.

As a seasoned Digital Marketer with over 15 years of hands-on experience, I offer a robust track record in driving successful digital marketing campaigns and initiatives. My deep expertise in Analytics, coupled with a solid background in Search Engine Marketing (SEM) and Email Marketing, allows me to deliver exceptional results tailored to meet business objectives. Based in the Netherlands, I am well-versed in the European digital landscape and data privacy regulations GDPR/DMA. Comprehensive knowledge in data analysis and reporting, with proficiency in Google Analytics 4 (GA4) and Google Tag Manager (GTM). Toolset Proficiency: Google Tools: Google Tag Manager (GTM), Google Ads, Google Analytics 4 (GA4), Campaign Manager 360 (CM360), Display & Video 360 (DV360) Social Media Ads: Facebook Ads, TikTok, Pinterest, SnapChat, LinkedIN, Reddit, X Consent Management Platforms (CMP): Expert in implementing and managing CMP tools such as Cookiebot, Onetrust, Quantcast, Amasty, CookieYes, CookieScript and IUbenda to ensure compliance with data privacy regulations. E-commerce Platforms: Proficient in working with various e-commerce platforms including Hybris SAP, Magento 1&2, Lightspeed eCommerce, Shopify, WordPress - WooCommerce, Prestashop, OpenCart, and Shopware 5&6. Other Platforms: Hubspot, Triple Whale, Posthog, Zoho, Pipedrive, Segment, Pipedrive, Mixpanel, Systeme-io Professional Experience: IPG Mediabrand (KINESSO), DELL Computers, KLM, Transavia, Schiphol Group, Rexel Services (not limited): Server-side migrations (via GCP, Taggrs, Stape) Audit and fix measurement & tracking issues (Offline) CAPI Conversion tracking for any type of (ads) platform Implement consent mode v2 (Cookiebot Agency Partner) Implement Google Ads dynamic retargeting Implement & configure GA4 and GTM ecommerce tracking Implement & configure Google BigQuery Workshops: GA4, GTM Server-side Should you have any other related Analytics or Data requests I would love to hear it. Best, CJ