const profile = {
name: 'Marcin Kozak',
role: 'Senior Full-Stack Engineer / Developer',
experience: '20+ years of experience',
specialization: 'e-commerce, scalable systems',
}
About Me
Programming is my craft and my pleasure rolled into one. What I find most rewarding is discovering elegant solutions - ones that are optimal, clean, easily testable, and intuitive for any developer who looks at the code. Before I write a single line, I make sure I understand the business intent - only when I have the full picture of what and why we're building can I design something that truly works.
My approach: understand the problem, design the solution, deliver value. Every line of code I write serves a business purpose and must be maintainable in the long run.
[ai] I use opencode with cost-effective language models for prototyping, code exploration, debugging, and TDD test generation. AI handles routine tasks while I focus on architecture and quality.
Key Traits
I make technical decisions autonomously and deliver without supervision
I design scalable solutions built for future change
I optimize systems for speed, cost, and reliability
TDD, code review, and clean code are my standards
I quickly adapt to new technologies and business contexts
Experience
Senior Full-Stack Developer @ Polcar PPH
Lead architect and developer of Polcar's first web-based B2B e-commerce platform (automotive parts), serving a catalog of 100,000+ products and handling ~40% of company revenue. The platform (catalog.polcar.com) replaces a previously desktop-only solution — migration in progress. Development and maintenance of smaller landing pages for in-house brands.
- ▹ Lead architect and developer of the B2B e-commerce platform — the company's first web application
- ▹ Launched platform handling 100,000+ product catalog and ~40% of company revenue, migrating from desktop to web
- ▹ Optimized data delivery from complex, heavy source databases — caching layer, query optimization, DB structure for read performance
- ▹ Data integration from internal systems, normalization and data cleaning
- ▹ Image delivery optimization with protection against unauthorized duplication
- ▹ Internal CLI tool in .NET/C# for MS SQL to MySQL migration with schema transformation
- ▹ Translation repository management system and language file tooling
Senior PHP Developer @ ModulesGarden
Developed ecosystem modules for the WHMCS hosting management platform. Worked on custom solutions including an internal project management tool, e-commerce integrations (Magento 1 cart, Magento 2 payment gateway), and a new system serving as a WHMCS alternative. Contributed to the official modulesgarden.com company website backend.
- ▹ WHMCS module development and alternative WHMCS system
- ▹ E-commerce integrations (Magento 1 cart, Magento 2 payment gateway)
- ▹ Internal project management tool
- ▹ Backend of modulesgarden.com company site
Frontend Developer (Freelancer) @ Self-employed
Built websites from design mockups using HTML, CSS, and JavaScript. Collaborated with interactive agencies and direct clients.
- ▹ Delivered 30+ websites and landing pages
- ▹ Collaborated with advertising agencies
- ▹ Managed projects and budgets independently
Skills
Tools and frameworks I work with daily
Projects
Selected case studies
B2B/B2C E-commerce Platform
catalog.polcar.comLead architect and developer of the B2B/B2C e-commerce platform with an online product catalog (catalog.polcar.com). Responsible for optimizing data delivery from complex, heavy source databases and translating business requirements into performant web application solutions.
- ▹ Lead architect and developer of the platform
- ▹ Caching layer and query optimization for hundreds of thousands of products
- ▹ Data integration from internal systems, normalization and cleaning
- ▹ Image delivery optimization with duplication protection
Database Migration CLI (.NET)
Internal terminal tool for migrating data between MS SQL and MySQL with automatic type and schema transformation, including table merging while maintaining referential integrity.
- ▹ Migrated 100+ tables with type and schema transformation
- ▹ Reduced migration time from days to hours
- ▹ Custom logic for table relationship transformation
Multi-language Management System
Internal tool for managing translation repositories. Enables working with language files across multiple projects, automatic detection of missing translations, and data export into project structures.
- ▹ Interface for managing multiple languages simultaneously
- ▹ Automatic detection of missing translations
- ▹ Export/import to project formats
ModulesGarden - Company Website
modulesgarden.comCo-developed the backend of the official company website modulesgarden.com. Implemented business logic and integrated with internal systems.
- ▹ Backend of the modulesgarden.com company site
- ▹ Integration with internal company systems
- ▹ Business logic implementation
Contact
Got a question or an interesting project? Let me know.