Professional Experience

Detailed work history and project highlights.

Open Source Contributor & AI Evaluator

Freelance Work

May 2026 – Present
  • Contributed 6 merged pull requests to Builder.io's Agent-Native project (TypeScript, Node.js, React), including a core error-routing fix, improvements to the Content and Mail template applications, and developer tooling.
  • Designed and built Tasks, a personal task manager accepted as an official template application, implementing agent-native patterns in which AI agents and the UI share the same state and actions.
  • Reported security issues discovered while adopting the framework and shared product feedback directly with the Builder.io team.
  • Delivered freelance AI validation projects involving prompt engineering, prompt authoring and refinement, AI model evaluation, and evaluation of AI-generated outputs.
Balyasny Asset Management (BAM) logo

Senior Frontend Engineer

Balyasny Asset Management (BAM)

Mar 2025 – Feb 2026
Warsaw
  • Designed and delivered analytical views, working directly with risk managers to translate complex financial requirements into decision-support tools used by ~1000 users.
  • Built internal React dashboards enabling exploration of large-scale financial datasets with AG Grid and custom visualizations.
  • Developed an advanced chart editor using Highcharts, supporting multiple visualization types (including candlestick, scatter, and bar) with configurable axes, data series, styling, and data selection.
  • Implemented efficient data fetching and caching using TanStack Query, and optimized rendering through profiling-driven virtualization and reduced DOM manipulation, keeping high-volume data views responsive.
GroundFog logo

Siemens

Ground Fog

Dynamic Solutions

Feb 2024 – Feb 2025
Warsaw
  • Led frontend development within a 10-person team (3 frontend engineers) on a multi-tenant content platform (Vue, GraphQL) powering siemens.com, mentoring developers, driving code review practices, and working closely with product managers, designers, and QA.
  • Delivered core platform features for siemens.com, including AI-powered search, chatbot interfaces, and live translation used across a global multi-language platform.
  • Built and evolved a shared component platform (~30 reusable components) with interactive component documentation, consumed by multiple applications, improving UI consistency, reuse, and development velocity at scale.
  • Improved quality and reliability by introducing automated visual regression testing (Playwright) integrated into CI/CD, enabling safe evolution of the shared UI platform.
  • Designed URL-based environment routing, allowing developers, QA, and stakeholders to access production content across environments without manual data migration, significantly improving development and testing efficiency.
Diva-E logo

Mann+Hummel

Diva-E

Dynamic Solutions

Sep 2023 – Jan 2024
Warsaw
  • Developed advanced product discovery features using React, TypeScript, and GraphQL, including VIN-based search, dimension-based filtering, and smart search across a large automotive catalog.
  • Built search results, product detail pages, and 360° product visualizations, improving catalog navigation.
Dynamic Solutions logo

WebSight CMS

Dynamic Solutions

Apr 2021 – Aug 2023
Warsaw
  • Led frontend development of a visual CMS platform built with React, mentoring 4 frontend engineers and working closely with designers and backend engineers on REST APIs and platform architecture.
  • Designed and built a true WYSIWYG page editor using an overlay system synchronized with an iframe-rendered page.
  • Led evolution of the frontend platform, including migration to TypeScript and React Hooks, refactoring of the editor architecture and state management, and ESM-based plugin integration.
  • Delivered core CMS capabilities including inline editing and content tree interactions while evolving a plugin-based editor architecture (6 editor plugins) and ensuring embedded pages rendered correctly inside the editing environment (e.g., normalizing viewport units inside an iframe).
OLX Group logo

Software Engineer

OLX Group

Dec 2019 – Jan 2021
Poznań
  • Developed authentication systems for a large-scale marketplace using Kotlin, Java, REST APIs, and AWS Cognito, implementing core user flows including login, registration, and password recovery.
  • Contributed to migration of millions of users to AWS Cognito while introducing security features such as suspicious login detection.
  • Designed secure internal tooling enabling Customer Support to manage blocked accounts independently, eliminating 15–20 daily engineering interventions.
  • Improved observability and error tracking using New Relic and Sentry.
No Spoon Tech Lab logo

Full-stack Web Developer

No Spoon Tech Lab

Jun 2018 – Aug 2019
Spain
  • Built a real-time messaging platform for an online gaming product using React, KotlinJS, and the XMPP protocol — message synchronization, presence handling, and live updates across connected clients.
  • Implemented custom server-side rendering for the React application in Node.js.
Appchance logo

Junior Frontend Developer

Appchance

Jan 2018 – May 2018
Poznań
  • Developed reusable UI components and client-side features using JavaScript and Ember.js across multiple projects.
Pearson IOKI logo

Junior Java Developer

Pearson IOKI

Jul 2016 – Dec 2017
Poznań
  • Developed REST APIs for an e-learning platform using Java, Kotlin, Spring Boot, and MongoDB within a microservice architecture, working in cross-functional Scrum teams (~20 engineers across two collaborating teams).