Arun Singh G.

Full Stack Developer | AI Developer | AI Solutions | React | Python

🏆 Top Rated Plus | ✅ Top 2% on Upwork | ⏳ 100% Job Success Generative & Agentic AI | AI Automations | AI Agents | LLMs & RAG | Full-Stack Engineering | Custom Web & Software Development | Digital Transformation I build AI-powered SaaS platforms for founders and ship them to real users, not demo day. Over 8 years I've launched subscription products across EdTech, LegalTech, and consumer AI. My lane is specific: React/Next.js frontends, Supabase or FastAPI backends, Stripe billing, and AI features that actually work in production. PROBLEMS I SOLVE FOR FOUNDERS: • Multi-tenancy done right. Schema-per-tenant and database-per-tenant architectures where one client's data can never leak into another's, even through a software bug. Isolation enforced at the infrastructure level, tested on every code push. • Systems that survive the real world. I designed an offline-first POS platform where terminals keep taking orders and processing payments through a full internet outage, with bidirectional sync and defined conflict-resolution rules when connectivity returns. • Billing that doesn't leak revenue. Full Stripe subscription lifecycles: webhooks with idempotency, grace periods so paying users never get falsely downgraded at renewal, tier limits enforced server-side. I've reconciled Stripe + Apple StoreKit + Google Play Billing into a single subscription source of truth. • AI features built for production load. Async pipelines, rate limiting enforced atomically in the database, third-party AI API costs treated as a first-class constraint, and capacity planning before launch, not after the outage. • Scaling past the MVP. Connection pooling, composite indexes, backpressure control, background job recovery after crashes. The unglamorous engineering that decides whether your product holds at 10x users. RECENT LAUNCHES: → ACE MMI: AI medical interview prep SaaS (UK market). AI scoring, speech analytics, personalized feedback across 8 competencies. React 18 + TypeScript, Supabase, Stripe. 1,000+ users in production. → NiceTry: Consumer AI content-detection app live on iOS, Android, Chrome, and web, built for a 650K-subscriber creator audience. Supabase RLS, server-side API security, three billing rails reconciled into one subscription model. → ImmigLens: Compliance SaaS for Canadian immigration professionals. Automated evidence capture with Playwright, stateful scheduling with crash recovery, full async FastAPI backend, audit-grade security, complete Stripe billing lifecycle. → Rose POS: Multi-tenant restaurant POS platform. Offline-first architecture, per-tenant database isolation, real-time WebSocket control, 80% test coverage enforced in CI. **STACK I SHIP WITH:** • **Frontend:** React, Next.js (App Router), TypeScript, Tailwind CSS, shadcn/ui • **Backend:** Supabase (Postgres, Auth, RLS, Edge Functions), FastAPI, Node.js/NestJS • **AI & LLM Infra:** OpenAI API, Claude API, DeepSeek, LangChain, LlamaIndex, LiteLLM, vLLM • **Agentic Workflows & Multi-Agent:** CrewAI, AutoGen, LangGraph, tool-calling, async AI job queues (Celery/BullMQ) • **Search, RAG & Vector DBs:** Hybrid Search, reranking (Cohere), pgvector, Pinecone, Qdrant, ChromaDB • **AI Observability & Evals:** LangSmith, Helicone, Arize Phoenix, Promptfoo • **Billing:** Stripe (subscriptions, webhooks, Customer Portal), StoreKit 2, Google Play Billing • **Infra:** Vercel, AWS, Docker, GitHub Actions CI/CD, PostgreSQL performance tuning • **Tooling:** Claude Code, Cursor, Copilot daily. AI-assisted development without cutting corners. HOW I WORK WITH FOUNDERS: I'm not a ticket-taker. I'll challenge scope that doesn't serve the product, flag risks before they cost you money, and give you the realistic timeline: the one that holds, not the one you want to hear. You'll always know where your project stands. Whether you need an AI MVP built in weeks or an existing product re-architected to scale, message me with your goals and timeline. I respond within 1-2 hours. Full Stack Developer | Full Stack Engineer | React Developer | React.js Developer | Next.js Developer | NextJS Developer | Node.js Developer | NodeJS Developer | TypeScript Developer | JavaScript Developer | Frontend Developer | Backend Developer | MERN Stack Developer | Python Developer | Django Developer | SaaS Development | SaaS Application Development | Product Engineer | Software Engineer | Technical Lead | Web Application Developer | Web App Developer | Custom Software Development | MVP Development | Next.js Development | Node.js Development | Python Development | API Development | API Integration | REST API | GraphQL API | Microservices | Monolithic Architecture | Scalable Architecture | Multi-Tenant SaaS | Multi-Tenant Architecture | PostgreSQL | MongoDB | AI Integration | OpenAI AP I Claude API | LLM IntegrationGenerative AI | AI AgentsAgentic AI | AI AutomationAI SaaS | Custom AI Solutions