
Przemyslaw S.
Senior Fullstack Engineer
Skills

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Werkervaring
Freelance Full Stack Developer
Szelenberger.pl • Freelance
Oct 2008 - Present • 18 yrs
Developed websites and e-commerce platforms for local businesses. Built both frontend and backend functionality using JavaScript, PHP and MySQL, including WordPress and PrestaShop-based projects.
Senior Full Stack Engineer
Makimo • Fulltime
May 2026 - Jul 2026 • 2 mos
Developed frontend features for the Election TouchScreen TV App using React and TypeScript. Worked with Zustand, React Query, Zod, SCSS and BEM, integrating the frontend with REST APIs and WebSockets. Maintained code quality through unit and end-to-end testing, code reviews, and automated testing with Vitest, React Testing Library and Playwright.
Senior Full Stack Engineer
WATS • Fulltime
Aug 2023 - Sep 2025 • 2 yrs 1 mo
Developed frontend and backend features for the Parametrization App, a tool used to configure a transactional system. Contributed to architectural decisions and technical design, and created internal tools to improve developer experience. Built a custom frontend build and deployment pipeline using Gulp.js for a legacy Ext JS and RequireJS environment. Led remediation work following a security audit, identifying and fixing vulnerabilities across both frontend and backend. Worked with JavaScript, TypeScript, Node.js, Ext JS, Backbone.js, PostgreSQL, Redis and WebSockets, with a strong focus on testing, maintainability and code quality.