Zain U.

Next.js | React | Supabase | PostgreSQL | Row Level Security | Stripe Connect | Claude and OpenAI | TypeScript | Python | FastAPI Full Stack Developer and Supabase Expert. I build Next.js and Supabase MVPs, integrate Supabase with the tools you already run, add LLM and AI features to live products, and audit RLS before launch. 5 years, 30+ production apps, Top Rated, and 4 of my last 11 Upwork clients hired me again. WHAT I BUILD → Next.js, React or Svelte MVPs on Supabase, from spec to paying users: auth, admin panel, booking system, Stripe Connect marketplace payouts → Supabase backend and integration work: Auth, RLS, JWT, Edge Functions, real-time sync, and connecting Supabase to Webflow, Make (Integromat), GoHighLevel and APIs → LLM and AI integration inside a production app: Claude and OpenAI APIs, AI assistants hardened for production, tool calling, structured output, RAG → Pre-launch RLS and Edge Function audits, Supabase Auth and JWT fixes, debugging new integration issues → Finishing apps someone else started: Lovable and other AI-built codebases, half-done MVPs, pipelines nobody documented RECENT WORK • Telemedicine MVP on Next.js and Supabase. Started as a $60 paid test task, became the full Phase 1. The client: "The authentication system, doctor directory, booking flow, and admin panel were all delivered on time and exceeded my expectations." • EdTech MVP with secure QR peer matching and real-time sync on Supabase and React. A broken RLS policy blocking a UK schools launch, fixed in 6 days against a 2-3 week estimate. • 9-month backend and integration engagement: Supabase plus Webflow plus Make automations. • Stripe Connect marketplace MVP on Next.js. The client came back for the website too. • An LLM app taken to market on Supabase, Svelte and TypeScript. The client: "I've hired a bunch of engineers off of Upwork over the years, and none of them are in his league." • Pre-launch security audit of a Lovable-built Supabase app holding minors' PII: RLS, IDOR, privilege escalation, Stripe webhook verification. • Verified and documented a real-time data pipeline (Next.js, Prisma, Supabase) for the team inheriting it. SUPABASE AND POSTGRESQL • Database design, migrations, indexes and constraints on live production data • RLS policies for multi-tenant isolation, SECURITY DEFINER, role-based access, audit trails • Postgres functions and triggers, state machines enforced in the database • Supabase Auth, Edge Functions, Realtime, Storage, signed URLs, private buckets 20+ RLS policies for a GDPR-compliant telemedicine marketplace. AI, LLM AND RAG • Claude API, Claude Vision, GPT-4o, MCP servers, multi-provider failover and token-cost tracking • Hybrid RAG with pgvector and Postgres full-text, reranking, inline citations • Eval harnesses and confidence scoring, so a failing AI answer is caught before a user sees it An AI legal-ops system drafting cited court letters, every citation traced to its source document. STRIPE AND PAYMENTS • Stripe Checkout, subscriptions, Stripe Connect Express, split payouts, refunds • Webhook signature verification, idempotency keys, reconciliation • Race-safe booking and payment state machines STACK Frontend: Next.js, React, TypeScript, JavaScript, Svelte, SvelteKit, Tailwind, shadcn/ui, TanStack Query, Zod, tRPC Backend: Supabase, Node.js, Python, FastAPI, Django, Prisma, REST API Database: PostgreSQL, Supabase, pgvector Payments: Stripe Checkout, Stripe Connect, webhooks AI: Claude API, OpenAI, LangChain, RAG, embeddings, LLM integration Integrations: Webflow, Make, GoHighLevel, n8n, Zapier Infra: Vercel, AWS, Docker, GitHub Actions Testing: Vitest, Playwright, Pytest HOW I WORK • Daily written updates. Blockers flagged early, never silence. • I read existing code before I change it, and I fix what you hired me for without a rewrite. • A paid test task or a small audit first is fine by me. Two of my repeat clients started exactly that way. Message me or click Invite to Job for an honest scope and timeline. Response within 2 hours (GMT+5).