Full Stack Developer based in Bangkok, Thailand, with hands-on experience shipping complete web systems — from database schema design to frontend UI.

I focus on building systems with real complexity: multi-role access control, stateful workflows, conflict-checking logic, and automated processes. My projects go beyond CRUD — solving real business problems such as rental lifecycle management, payment verification, stock reservation systems, and repair workflow tracking.

• 🎓 Business Computer — Mahasarakham University (2021–2025)
• 🔐 Experienced in JWT Auth, RBAC, RESTful API design
• 📦 Production deployments on Ubuntu Linux + PM2
• 📚 Currently learning NestJS · System Architecture · Advanced Backend Patterns
• 🤝 Open to Full Stack · SaaS · Open Source collaboration

Next.js Fullstack · Mar 2026

Full-stack e-commerce system built with Next.js App Router, combining frontend and backend in a single architecture with customer and admin experiences.

What makes it interesting:

• Fullstack architecture using Next.js (Server Actions + Route Handlers) — no separate backend service
• Role-based system: CUSTOMER / ADMIN with protected routes
• Shopping cart with optimistic UI updates and real-time calculation
• Order lifecycle: PENDING → PAID → SHIPPED → DELIVERED with status history
• Payment slip upload with admin verification
• PromptPay QR code generation for payments
• Admin dashboard with revenue stats, growth indicators, and stale-order alerts
• Product & category soft-delete / restore system
• Multi-image upload with main image selection via ImageKit CDN + Sharp processing
• Server-side caching ("use cache") with tag-based revalidation across products, orders, users, and cart
• Input validation using Zod and secure JWT (HTTP-only cookie) authentication

Next.js React TypeScript PostgreSQL Prisma Tailwind CSS JWT ImageKit Zod

PERN Stack · Feb 2026

Back-office admin panel for managing the full rental lifecycle — booking, payments, deposits, and penalties.

What makes it interesting:

• Multi-step workflow engine: PENDING → CONFIRMED → ACTIVE → RETURNED → COMPLETED
• Payment slip verification with approve/reject logic — uses PostgreSQL row-level locks (FOR UPDATE, pg_advisory_xact_lock) to prevent race conditions on concurrent approvals
• Deposit state machine: HELD / REFUNDED / DEDUCTED with partial refund and deduction support
• Penalty module: LATE / DAMAGE / LOST with auto-generated invoices (INV-YYYYMMDD-XXXX)
• Stock reservation conflict-checking across overlapping date ranges with emergency release
• Reports: monthly revenue charts (last 12 months), top 10 products, overdue tracking
• Audit log system with admin action tracking and cleanup support
• RBAC middleware restricting admin-only access

React Node.js Express PostgreSQL Prisma JWT

PERN Stack · Dec 2024 – Feb 2025

Full-stack rental platform with a Customer App and an Admin Panel — dual codebase, dual role system.

What makes it interesting:

• Dual-role system: Customer App (React) + Admin Panel (React) as separate frontends
• Full rental lifecycle with status tracking: wait → pay → send → cancel
• Return workflow with return status: pending → Waitingtocheck → approved / rejected / overdue
• Payment slip upload and shipping proof image management
• Cart with rental duration selection, discount calculation, and auto-return date computation
• Shop bank accounts displayed at checkout with transfer info submission
• Wishlist using localStorage (no login required to save items)
• Product image gallery with multi-image upload
• Bulk import via Excel (products and categories via ExcelJS)
• Admin dashboard with Bar/Line chart toggle (Chart.js) and 10 summary metric cards
• Deployed on Ubuntu Linux with PM2

React Node.js Express PostgreSQL Prisma JWT Chart.js ExcelJS

MERN Stack · Jul 2024 – Oct 2024

Responsive store management system for mobile retail — covering stock purchasing, sales processing, and repair workflows.

What makes it interesting:

• Sell workflow with serial number lookup and pending sell list confirmation
• Bulk stock entry supporting up to 10,000 units per transaction
• Repair/service job tracking with full CRUD
• JWT authentication with two role levels (admin / user)
• Dashboard with monthly income bar chart (Recharts) and business summary stats
• Company settings with upsert pattern (create on first save, update thereafter)
• Deployed on Ubuntu with PM2

Next.js Node.js Express MongoDB Prisma TypeScript Tailwind CSS JWT

React · Vite · https://patsarun2545.github.io/profile/

Personal site showcasing projects and skills.

React Vite GitHub Pages