Will I work with you directly?

Yes. F Koin Tech is my independent practice. I scope the project, write the code, deploy it and support it. There is no account manager or outsourced team in between.

Can you take over an application someone else built?

Usually, yes, and it is often the cheaper answer. I review the codebase, keep what works, fix what's fragile and rebuild only the parts genuinely holding you back.

How do you use AI in development?

I use AI agents and AI-assisted workflows for research, test drafting, codebase analysis and documentation. They make delivery faster; they don't make decisions. Everything that ships is reviewed by me.

Can you integrate AI or LLMs into our product?

Where it removes measurable work, yes: document handling, search, classification, drafting and summarising. I'll also tell you plainly when a conventional solution would be cheaper and more reliable.

Can you work alongside our internal team?

Yes. I can work inside your repository, standards and review process, or own a defined part of the system end to end.

How do you estimate a project?

After a discovery call, not before. I map the requirements first, then give you a written scope and estimate with milestones.

Independent developer

Senior full-stack developer for SaaS, AI integrations and custom software

I'm Gurwinder Singh. For 9+ years I've built scalable web applications, SaaS products and business systems for clients worldwide. You work with me from the first call to launch and long-term support, with no account managers and no handoffs.

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Gurwinder Singh

Senior Full-Stack Developer · SaaS, AI Integrations & Custom Software

Years experience: 9+
Projects delivered: 90+
Clients worldwide: 30+

CanadaUnited StatesIndia

Full-stack web apps

SaaS products

AI & LLM integrations

CRM & ERP systems

Services

What I can build for you

From a single integration to a full SaaS product, plus the maintenance and support that keep it running.

From database to interface

Full-Stack Web Development

Production web applications in React, Next.js and Node.js: customer portals, dashboards and internal tools, designed, built and deployed by one developer.

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AI applied to real workflows

AI & LLM Integrations

LLM features built into your product or operations: document handling, search, drafting, classification and AI agents.

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Take your product to market

SaaS Application Development

Multi-tenant architecture, authentication, roles, subscriptions and the admin tooling a SaaS product needs from day one.

Run operations from one system

CRM & ERP Solutions

Pipelines, inventory, finance and reporting built around how your business actually works.

Connect what you already run

API Development & Integrations

REST APIs, payment gateways and third-party services wired together reliably.

Take over and stabilise

Existing Application Maintenance

Bug fixes, upgrades, performance and security work on applications you already run, including code someone else wrote.

A developer who knows your system

Ongoing Development Support

Regular development time for new features, improvements and fixes, from the same developer every time.

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Work with me

One developer, accountable end to end

You work directly with the developer who designs, builds and supports your software.

You talk to the developer

The person who scopes your project designs it and writes the code. No account manager relaying messages.

AI-assisted, human-reviewed

AI tools speed up research, testing and documentation. Every decision and every line that ships is reviewed by me.

Accountable after launch

I maintain what I build, so the person fixing an issue is the one who wrote the code.

More about me

Selected projects

Work I've built and shipped

A selection of the platforms, SaaS products and internal tools I've delivered for clients under F Koin Tech.

Web Application

Technology

A stack chosen for how long it has to last

React, Next.js, Node.js, TypeScript, PostgreSQL, MongoDB, Prisma, AWS and AI integrations, chosen for maintainability, not novelty. Your system should still be supportable in five years, by any competent developer.

Frontend

React
Next.js
TypeScript

Backend

Node.js
Express
Prisma
PHP

Mobile

React Native
Flutter
Android
iOS

AI

OpenAI
Claude
Gemini
LLM integrations
AI agents

Cloud

AWS
Azure
Cloud hosting

Database

PostgreSQL
MongoDB
MySQL

Works with the tools you already pay for

Payments, commerce, logistics, accounting, productivity. If it has an API, I can connect it rather than replace it.

Browse integrations

Problems I solve

If any of this sounds familiar, you're in the right place

Most of my projects start with one of these. Here's what I do about them.

The business runs on spreadsheets

One system of record replaces the files everyone edits separately.

Manual work eats the day

Automate the repetitive steps so your team spends time on decisions, not data entry.

Your tools don't talk to each other

API integrations connect the systems you already run, end to end.

Reporting takes days

Live dashboards answer the questions leadership asks, on demand.

The software is older than the process

Rebuild on a modern stack without stopping operations.

Growth breaks the workflow

Systems designed for the volume you'll have in three years, not last year.

How I work

Understand the business first, then build

Four steps from first conversation to software your team runs on, and what your week looks like afterwards.

Understand

I map how the business runs today: the systems, the real workflows, and where time is lost.

Recommend

What to automate, integrate or leave alone, with a written scope and estimate before any build.

Build

Delivered in weekly increments you can see, test and steer.

Run and support

Deployed with monitoring and training, then maintained by the developer who built it.

How it runs todayAfter it's built

Spreadsheets are the system of recordOne platform every team works from
Approvals chased over email and chatWorkflows that route and record themselves
The same data keyed in three placesEntered once, correct everywhere
Tools that don't talk to each otherIntegrated systems, one flow of data
Reporting assembled by hand, days lateLive dashboards, answers on demand

Testimonials

What clients say

Feedback from businesses whose software I've built and supported.

Gurwinder is a willing and very eager developer who will do anything with 100% quality. He had a good experience in android app development. Happy with his work and will hire for sure!!

Muhammad Saqib

Pakistan

Gurwinder did an exceptionally good job and completed it before the deadline. He has good command in React and other programming languages we surely work with him again in near future.

Pushpender Gaur

India

Upwork

Extremely talented, understands requirements and points it well enough even in action. Has got good hand over skillset, and mainly delivers in time. Thanks again for your efforts

Arik Shah

India

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Pricing

Clear starting prices

See where a project starts in your currency, then get a quote scoped to what you need.

Custom software development

Software built around how your business actually works, from an internal tool to a complete business system.

Starting at

₹50,999one-time

Requirement discovery and a written scope before development
A web application built around your core workflow
Responsive interface for desktop and mobile browsers
Testing before launch
Deployment and handover

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Every package, by category

Websites
CMS & CRM
E-commerce
Custom software
Redesign & support
SEO & social media

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Questions

What clients ask before a project starts

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Let's talk

Have a project in mind? Let's talk it through

Tell me what you're building or what isn't working. You'll get an honest view of the right approach, a written scope, and a straight answer if custom software isn't what you need.

Hire me

What happens next