About
Gaurav Singh Karki— Full-Stack & AI Developer
I'm a full-stack engineer who builds for the web and mobile in any tech or framework. Beyond apps, I work across Python automation, testing, debugging, security, and deployment — taking products from idea to production. I've shipped encrypted cloud storage, multi-tenant SaaS, payment-routing engines, AI platforms, and consumer products, always with a focus on clean architecture, real integrations, and measurable outcomes.
Based in India and working with clients worldwide — the US, Europe, Hong Kong, and India — as a Top Rated freelancer on Upwork with a 100% Job Success Score. Co-founder and director of Cosmo Clan, a product studio. Usually replies within a day.
30+
Products in production
5+
Years of experience
100%
Upwork Job Success Score
1,442
Hours on Upwork
5.0
Average client rating
12
Happy clients
Services
What you can hire me for — every service backed by shipped, production work.
Full-Stack Web Development
End-to-end web applications with Next.js, React, TypeScript, Node.js, Laravel, PHP, Python, and FastAPI — from architecture and database design to a polished, responsive frontend.
AI & LLM Development
Production AI systems: RAG pipelines, AI chatbots, LLM tool-use and agent integrations with OpenAI and Anthropic Claude. Shipped work includes JARVIS RCSA, an enterprise AI platform used by banks, and a Next.js + FastAPI RAG chatbot.
SaaS Development
Multi-tenant SaaS platforms with subscriptions, per-tenant branding, encrypted credentials, and tenant isolation — like Captime, a compliance platform for Hong Kong company secretarial firms.
Payments & Billing
Stripe, Razorpay, Adyen, and PayPal integrations: checkout, recurring subscriptions, webhooks, invoicing, refunds, payment routing, and chargeback handling. Built multi-gateway platforms processing real transaction volume (Zettable, ExRouter).
API Development & Integration
REST APIs with authentication, rate limiting, and Swagger/OpenAPI documentation, plus third-party integrations: KYC (Sumsub), e-signatures, geo-IP, email, and analytics.
MVP Development for Startups
Idea to production fast: scoping, clean architecture, real integrations, and deployment — 30+ products shipped, so common pitfalls are already solved.
Security & Performance
Security audits, AES-GCM encryption, zero-knowledge architectures (CloudPlaza), scalability reviews, and debugging of existing codebases — hired by Upwork clients specifically for security hardening.
Deployment & Infrastructure
Vercel, AWS, Azure, Railway, Docker, Nginx, VPS/Linux, and CI/CD with GitHub Actions — taking projects from repository to reliable production hosting.
Technology stack
Frontend
Next.js · React · TypeScript · Tailwind CSS · shadcn/ui · Framer Motion · TanStack Query · PWA
Backend
Node.js · Express · Laravel · PHP · Python · Flask · FastAPI · REST APIs
Database & ORM
PostgreSQL · MySQL · Prisma · Supabase · Redis
AI / LLM
Anthropic Claude · OpenAI · LLM Tool-use
Auth & Security
NextAuth · JWT · Encryption (AES-GCM) · Multi-Tenant Isolation
Payments & Billing
Stripe · Razorpay · Adyen · PayPal · Subscriptions & Webhooks
Cloud, Infra & Deployment
Vercel · Railway · AWS · Azure · Docker · Nginx · VPS / Linux · CI/CD (GitHub Actions)
Tooling & Testing
Git / GitHub · Automation Scripting · Testing & Debugging · Swagger / OpenAPI · Analytics (GA4)
Experience
Co-Founder & Director — Cosmo Clan
Mar 2025 — Present · Almora, India · Remote
Co-founded and lead a product studio, driving direction across engineering, product, and client delivery.
Software Engineer — GLiN Softwares Pvt. Ltd
May 2023 — Dec 2025 · Chandigarh, India · Hybrid
Full-stack developer building scalable web platforms, CRMs, SaaS products, and AI-powered solutions for global clients.
Software Engineer — Max Ads Media
May 2023 — Jun 2025 · United States · Remote
Worked remotely on high-conversion marketing platforms and landing-page systems for performance-driven campaigns.
Selected work
13 shipped projects — here are the highlights.
Hiring FAQ
Everything clients usually ask before starting a project — pricing, process, AI capabilities, and logistics.
How much does it cost to hire Gaurav?
Pricing depends on scope. Gaurav works both fixed-price and hourly, through Upwork or a direct contract. Send a short description of your project via the contact form, email, or WhatsApp and you'll get a clear estimate — usually within a day.
How does a project with Gaurav start?
Reach out with what you want to build. Gaurav reviews the scope, asks clarifying questions, and proposes an approach with milestones and an estimate. Once agreed, work starts with regular progress updates — clients consistently mention smooth communication and quick responses in their reviews.
Does Gaurav work fixed-price or hourly?
Both. Well-defined scopes suit fixed-price milestones — most of his Upwork contracts are fixed-price with 5-star outcomes. Ongoing or evolving work suits hourly; he has logged 1,400+ tracked hours on Upwork.
Can Gaurav build a RAG chatbot on my company's data?
Yes — this is a core specialty. He has delivered production RAG systems including a Next.js (TypeScript) + FastAPI chatbot with a complete RAG pipeline for an Upwork client, and contributed 528 commits to JARVIS RCSA, an enterprise document-AI platform used by banks that ingests policies, SOPs, and contracts.
Which AI models and APIs does Gaurav work with?
OpenAI and Anthropic Claude APIs, including LLM tool-use and agent integrations, plus the orchestration around them: vector search and retrieval, verification passes that gate AI output quality, background job queues (BullMQ), and document export pipelines (Word, PowerPoint, PDF, BPMN).
Can Gaurav handle payments and subscription billing?
Yes. He has built entire payment platforms, not just checkout forms: Zettable, a multi-gateway billing platform (Stripe, Adyen, SolidGate) with recurring rebills, invoicing, refunds, and chargeback handling, and ExRouter, a payment-routing engine that distributes transactions across gateways to balance approval rates. Also Stripe, Razorpay, and PayPal integrations in client projects.
Does Gaurav deploy and host the finished product?
Yes — design to deployment. He ships to Vercel, AWS, Azure, Railway, and self-managed VPS/Linux with Docker, Nginx, and CI/CD via GitHub Actions, and can hand over documented infrastructure or keep maintaining it.
Can Gaurav join an existing team or take over a codebase?
Yes. Alongside greenfield builds he has worked embedded in teams for years (GLiN Softwares, Max Ads Media) and takes on existing codebases for audits, fixes, and features — including a security audit engagement that earned a 5-star review.
What timezone does Gaurav work in?
He's based in India (IST) and works with clients in the US, Europe, Hong Kong, and India, overlapping hours as needed and communicating async via email, WhatsApp, and Upwork. Clients note he was available when they needed him.
Will Gaurav sign an NDA?
Yes — reasonable NDAs and contracts are fine. Mention it when you reach out and it can be handled before any sensitive details are shared.
Why choose Gaurav over an agency?
One senior engineer who covers the whole stack — frontend, backend, AI, payments, security, and deployment — with direct communication and no hand-offs. The track record is verifiable: 30+ products in production, 100% Job Success on Upwork, 5.0 average rating, and live products you can open today.
Work with me
Available for freelance and contract projects worldwide. Reach me through the contact form, karkigauravsingh@gmail.com, WhatsApp, or Upwork.
Get in touchWhatsApp · GitHub · Upwork · LinkedIn · X