Available for work

Patrik Dinh

Building internal systems,automation and AI tools.

I build practical software for real workflows, with a strong focus on security, testing and whether the final system can actually be trusted in day-to-day use.

EmailGitHub

Work

Real systems built for everyday use, not just portfolio demos.

What you see here are public-facing versions of larger production systems. I share enough to explain the thinking and the work, but not the private logic, prompts and internal workflows behind them.

Lootea Operations System

A POS-first system that runs real day-to-day cafe operations.

An in-house cafe operations system built around real bubble tea workflows, not generic restaurant assumptions. POS is the center: checkout, orders, payments, receipts, labels and refunds, with the wider operation connected through products, employee cards, shifts, calendar sync, invoice AI, stock, recipes and reporting.

Built around the POS core: fast checkout, configured drinks, payments, receipts, labels and refunds.
Connects the wider operation through products, stock, recipes, employee cards, shifts, calendar sync, invoice AI and reporting.
Supports parked orders, split payments, cash rounding, refunds, vouchers and dual-currency receipts in daily use.
Connected to a custom Print Agent for instant receipts, drink labels and cash drawer actions without extra staff steps.

Challenge: Keeping checkout, products, staff, shifts, invoices, printing, permissions and reporting coherent in daily operation.

Print Agent

Local printing layer for a cloud-based POS system.

A local desktop bridge that makes a cloud-based POS behave like a native in-store system. Running on a Windows PC next to the cash desk, it handles receipt and label printing without browser dialogs, manual clicks or staff intervention.

Built to solve the real gap between a cloud POS and local in-shop printers.
Prints receipts with discounts, VAT, refunds and dual-currency totals (CZK/EUR).
Automatically prints a drink label for every confirmed item with zero extra barista steps.
Runs silently in the background, starts with Windows and is designed for day-to-day reliability.
Uses a custom REST API and secure HTTPS tunnel to connect cloud workflows with local hardware.
Turned slow, fragile browser printing into a workflow that feels like a native on-prem system.

Challenge: Browser printing was too slow and too fragile for live cafe workflow.

Lobby Mates

A squad planning app that helps friend groups decide what they can play together.

A real full-stack product for gaming groups. Lobby Mates brings Steam login, squad invites, shared libraries, play intent, Steam wishlist overlap, profile presence, suggested games, top picks, comparison filters and Discord room setup into one focused dashboard, with a public read-only demo for portfolio review.

Built around the practical question: what can this group play together right now?.
Uses Steam OpenID and Steam Web API for account identity, profile data, current activity, game ownership, playtime, public library sync and squad wishlist discovery.
Supports multi-squad membership, invite codes, active squad switching and leader/member permissions in one production database.
Ranks games with audit-friendly score breakdowns, readiness, ownership, play intent, wishlist overlap, sort modes and member comparison instead of a generic list.
Includes cards/list views, setup guidance, paginated browsing and status/platform/genre/search filters for a dashboard that stays usable as the squad library grows.
Adds an optional Discord integration for private squad text and voice rooms managed from the app.
Includes a public read-only demo route powered by a viewer role, normal session cookies and server-side write guards.

Challenge: Making group game choice clear while keeping Steam sync, invites, permissions and Discord state reliable.

VOUCHER GENERATOR

Automated PDF voucher generation with live preview, batch creation, and Supabase-backed sequencing.

A precision tool for marketing operations that replaced slow, error-prone manual voucher preparation with a controlled PDF generation workflow. It handles print-ready output, batch creation, sequential IDs and DEMO/PROD safeguards without sacrificing layout accuracy.

Replaced a manual voucher workflow with a faster, more reliable batch process.
Generates print-ready PDF vouchers using a high-resolution A4 template.
Supports batch generation of up to 200 vouchers in a single transaction.
Uses pixel-perfect X/Y coordinate mapping with live preview for layout accuracy.
Handles sequential numbering safely via Supabase in PROD and sandbox logic in DEMO.
Protects production data with a clear DEMO mode, watermarking and disabled writes.

Challenge: Keeping print precision, batch sequencing and DEMO/PROD safety reliable at once.

Invoice AI Extractor

AI-powered invoice data extraction using Google Gemini.

An AI-powered invoice extraction pipeline built for real accounting workflows, not demo screenshots. It converts complex PDF invoices into a structured JSON schema, then validates, corrects and normalizes the result so it can be used directly in our internal ERP.

Challenge: Making AI extraction trustworthy enough for accounting and ERP use, not just demos.

About

About me

I got into software because I like figuring things out and making them actually useful. Most of what I build lives somewhere between internal tools, automation and practical systems for day-to-day work, usually in places where generic software does not fit very well.

I use AI tools a lot, but I am not interested in just getting an app on the screen and calling it finished. I care about the parts that decide whether something is actually usable: security, testing, validation, reliability, and whether it still makes sense once real people start depending on it.

I am still early in my career, so I am learning constantly. But I already know I work best when I can take a messy problem, break it down, build something practical, and keep improving it as it gets used in the real world.

What I do

I build internal tools, automation and full-stack web apps for workflows that need more than a generic template.

Who I'm useful for

People who have a real workflow problem, not just a vague app idea, and want someone who can turn it into something practical and usable.

Where I'm still growing

Most of the systems I have built so far were built independently, so one area I am still growing in is the team side of software development - code reviews, shared ownership and larger engineering workflows.

A small truth

I probably spend more time thinking about edge cases than is healthy.