Piotr is available for hire
Hire PiotrPiotr Kuczynski
Verified Expert in Engineering
JavaScript Developer
Berlin, Germany
Toptal member since February 19, 2016
Bio
Piotr is a highly motivated, proactive, and ambitious software engineer with outstanding technical skills and over 20 years of experience. As an entrepreneurial professional and Agile evangelist, he has a strong personality and experience managing international and distributed teams. Piotr specializes in web development, performance optimization, and architecture design and is interested in usability and slick user interface designs.
Portfolio
Odevly
React, TypeScript, Next.js, Firebase Web SDK, Vitest, Vercel
On
Apache Kafka, RFID, Storybook, Enterprise Resource Planning (ERP)
MenoHealth, INC
Node.js, REST APIs, PostgreSQL, Database Design, Wearable Technology...
Experience
- PostgreSQL - 20 years
- JavaScript - 20 years
- React - 10 years
- Node.js - 10 years
- TypeScript - 8 years
- Amazon Web Services (AWS) - 7 years
- Google Cloud Platform (GCP) - 5 years
Work Experience
Lead Software Architect
2026 - 2026
Odevly
- Audited and optimized a Next.js application for performance and SEO, improving Core Web Vitals and organic search visibility.
- Rebuilt key pages with server-side rendering to improve load times and search engine indexing.
- Set up CI/CD pipelines from scratch and introduced Vitest end-to-end testing to catch regressions before deployment.
- Configured multi-region Vercel deployment and resolved authentication issues to improve reliability and uptime.
Technologies: React, TypeScript, Next.js, Firebase Web SDK, Vitest, Vercel
Senior Software Engineer
2026 - 2026
On
- Built RFID and EPCIS-based inventory tracking integrations connecting Nedap Harmony readers to internal retail systems for real-time stock visibility.
- Engineered event-driven data pipelines with Apache Kafka to process SSCC-level shipment and inventory events at scale.
- Fed real-time RFID/EPCIS inventory events into upstream ERP and inventory-management systems, extending the ERP integration expertise built during the prior engagement (EDI/Dynamics 365 middleware).
- Developed the EPCIS event-tracing service for RFID tags across the supply chain.
- Integrated with Nedap Harmony, the RFID location system synchronizes warehouse and store locations and resolves ambiguous location conflicts.
- Processed warehouse-receiving, store-shipment, and excess-inventory-notification events via Kafka, tracking SSCC through the fulfillment flow.
- Migrated the test suite from Jest to Vitest across the monorepo and containerized PostgreSQL and Redis for testing; built AdminJS admin panels for operations.
- Optimized database performance with targeted indexes on high-volume EPCIS event tables.
Technologies: Apache Kafka, RFID, Storybook, Enterprise Resource Planning (ERP)
Founding Back-end Engineer
2026 - 2026
MenoHealth, INC
- Architected and built a HIPAA-compliant women's health platform end-to-end in TypeScript, spanning React Native (Expo) mobile applications, a React web SPA, and a Hono, TypeORM, and PostgreSQL API.
- Designed a server-side survey engine that profiles users across life stage, symptoms, goals, and medical history to drive personalized onboarding.
- Built the back-end service and monorepo from scratch (Node.js, TypeScript, Hono, and PostgreSQL on AWS RDS) as the founding engineer.
- Stood up AWS infrastructure as code with Terraform/OpenTofu: ECS Fargate, ALB/WAF/ACM, CloudFront, Route 53, IAM Identity Center, and CI/CD across staging and production.
- Built back-end integrations ingesting health data from Apple HealthKit, Google Health Connect, and Terra, plus fixes to React Native wearable libraries.
- Built the "MenoScore" engine: a daily personalized physiological score with nightly recompute jobs, historical backfill, and prevalence tables.
- Built a server-driven onboarding survey engine and a partitioned symptom-tracking system, plus a notification system on a pg-boss job queue.
- Held general responsibility for HIPAA/PHI compliance, including a shared audit-logging package and observability with CloudWatch and Pino.
- Integrated LLM-powered narrative summaries (Claude/Anthropic API and Langfuse) and set up an AI-native, Claude-based automated code review pipeline in CI.
- Designed and implemented authentication and authorization using Better Auth, including session management and access control across the platform.
Technologies: Node.js, REST APIs, PostgreSQL, Database Design, Wearable Technology, Real-time Data, Role-based Access Control (RBAC), OAuth 2, Image Processing, Stripe, CI/CD Pipelines, Amazon Web Services (AWS), HIPAA Compliance, Docker, HIPAA, SOC 2, Compliance, GitHub Actions, Better Auth, iOS, Android, React, React Email, React Native, Amazon Simple Email Service (SES), Terraform, OpenTofu, Amazon Redshift, Amazon S3 (AWS S3), Hono, Zod, Zod Schema, Nx, Monorepos, Amazon Elastic Container Service (ECS), AWS ECS Fargate, Amazon Route 53, Astro, Strapi
Fractional Architecture Advisor
2026 - 2026
Envoyum
- Advised the founder on technical architecture for a multi-tenant SaaS platform, reviewing service boundaries, tenant resolution strategy, and data isolation in PostgreSQL.
- Reviewed architectural decision records and provided opinionated guidance on observability, workflow orchestration (BullMQ), and AI provider integration strategy.
- Guided the multi-tenant data model design, advising on tenant isolation, schema strategy, and PostgreSQL implementation patterns, including pgvector for embeddings.
- Provided architectural review of React performance optimization, advising on component decomposition and state management patterns to resolve INP bottlenecks.
- Shaped the AI integration and tooling strategy, advising on Cursor and Claude Code adoption, agentic safety governance, and multi-provider large language model (LLM) cost controls.
- Served as technical sparring partner to the founder, challenging assumptions and evaluating trade-offs on provider abstraction, circuit breakers, and resilient enrichment pipelines.
- Advised on multi-tenant authentication and authorization architecture, including tenant-scoped access control and identity isolation strategy.
Technologies: TypeScript, Redis, HTML, JavaScript, CSS, PostgreSQL, HTML5, React, Full-stack Development, Node.js, Supabase, Tailwind CSS, Agentic AI, Cursor AI, Claude Code, Multi-tenant SaaS, Pgvector, Vector Databases, BullMQ, Large Language Models (LLMs), AI Integration, Prometheus, Grafana, REST APIs, RESTFul APIs, Authentication, Authorization
Interim Tech Lead
2025 - 2026
Orcrist Technologies GmbH
- Defined and enforced architecture and coding standards across Node.js/tRPC and Next.js/React services.
- Delivered critical components: authentication and authorization flows, typed API contracts, performance improvements, and observability.
- Established reusable security and compliance primitives and evolved core product features (notifications, admin console, and data models).
- Collaborated with the Platform team on Kubernetes/CI-CD and Temporal-based workflow orchestration.
- Provided technical guidance across the engineering team, including on the platform's AI/LLM data pipeline (self-hosted inference, embeddings, and vector search).
Technologies: Better Auth, Node.js, TypeScript, React, Vite, GitHub Actions, Agentic AI, Large Language Models (LLMs), Temporal, PostgreSQL, Kubernetes, Authentication, Authorization
Senior Software Engineer
2025 - 2026
Social Gaming Room LLC
- Engineered a high-availability back-end service using Node.js and Express.js, centralizing the integration of 1,000+ gaming titles from various third-party providers into a unified REST API.
- Developed a secure financial processing layer to manage payment integrations and Sweep Coin redemption requests, ensuring data integrity and precision for cash prize transactions.
- Optimized the PostgreSQL database schema using TypeORM, which enhanced query performance and supported the platform's scaling requirements for a growing U.S. user base.
- Architected advanced error-recovery and fallback strategies, significantly improving system robustness and reducing downtime during third-party provider outages.
- Streamlined the GitHub Actions CI pipeline, reducing build execution times and enforcing strict TypeScript standards to catch potential runtime errors before they reached production.
Technologies: Node.js, TypeScript, PostgreSQL, TypeORM, REST APIs, Hash, Express.js, Routing Controllers, GraphQL, GitHub Actions, Testing, AI-generated Code, API Integration, Claude, Cypress, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Cursor AI, Agentic AI, Redis, Cloudflare, Cross-browser Compatibility, QA Automation, NestJS, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Stripe API, Payment Processing, Web Development, Identity Verification, React, APIs, Fintech, Payments, AI Tools, Cloud, Vibe Coding, Zod, Zod Schema, Consumer-facing Products, Modern JavaScript, Refactoring, Web Application Architecture, OpenAPI, Swagger, Sockets, Socket.IO, Error Handling, Sentry, Docker, SQL, Event-driven Architecture, Event-driven Systems, Terraform, Containerization, Prompt Engineering, Software Design, High-availability Systems, Payment APIs, Deployment, Automations, API Development, Dashboards, Database Architecture, Object Storage, Role-based Access Control (RBAC), Web Dashboards, RESTFul APIs, JSON, Third-party APIs, Webhooks, Cron, Back-end, OAuth, Clean Architecture, Middleware, Dependency Injection, Database Migration, Quality Assurance (QA), Database Design, Early-stage Startups
AI Engineer
2025 - 2025
An Online Freelance Agency
- Developed and curated large-scale post-training datasets (SFT, RLHF) specifically for multimodal agents, directly contributing to improved model performance in complex software engineering and STEM reasoning tasks.
- Containerized and orchestrated dozens of diverse open-source repositories using Docker, creating standardized, isolated environments for agent training and performance evaluation.
- Evaluated and refined complex software engineering problems derived from GitHub pull requests, transforming raw code into high-quality training data for LLMs in collaboration with OpenAI and SWE-Bench.
- Engineered sophisticated prompts and RLHF examples for TypeScript and JavaScript ecosystems, ensuring the accuracy and safety of model-generated code in enterprise-grade environments.
Technologies: TypeScript, React, Docker, Reinforcement Learning from Human Feedback (RLHF), Node.js, Claude Code, Testing, AI-generated Code, Artificial Intelligence (AI), Claude, n8n, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Cursor AI, Agentic AI, Supabase, Redis, QA Automation, Python, Large Language Models (LLMs), Databases, Documentation, Software System Architecture Development, Web Development, PostgreSQL, APIs, API Integration, AI Automation, AI Tools, Cloud, Replit, Vibe Coding, Zod, Zod Schema, Modern JavaScript, Web Application Architecture, OpenAPI, Swagger, Go, Error Handling, SQL, Containerization, Prompt Engineering, Software Design, Website Data Scraping, Automations, Scripting, Database Architecture, RESTFul APIs, JSON, Third-party APIs, OpenAI API, Back-end, Clean Architecture, Legacy Code, AI Agents
Senior Software Engineer
2025 - 2025
SYNLAB
- Architected and launched a greenfield data visualization platform from the ground up, translating vague business requirements into a production-ready React application that received high user acclaim.
- Engineered a secure authentication and authorization layer using Microsoft Identity Platform and OAuth 2.0, ensuring HIPAA-level compliance for sensitive medical diagnostic data.
- Developed complex statistical dashboards utilizing Recharts, providing clinicians with real-time visual insights into AI-generated test reports and laboratory trends.
- Optimized the front-end architecture using TanStack Query and Vite, delivering a bug-free, highly responsive Single Page Application (SPA) within an accelerated project timeline.
- Spearheaded the UI/UX implementation using Mantine and Tailwind CSS, independently making design decisions that improved data readability for non-technical stakeholders.
Technologies: TypeScript, React, Vite, TanStack Router, TanStack Query, Mantine, Zod, Recharts, Tailwind CSS, Python, Python 3, OAuth 2, Microsoft Identity Platform, Testing, Pixel Perfect, AI-generated Code, API Integration, Cypress, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Agentic AI, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), Mobile First, Large Language Models (LLMs), FastAPI, Documentation, SaaS, Software System Architecture Development, Web Development, Node.js, AI Automation, Artificial Intelligence (AI), AI Tools, Vibe Coding, Zod Schema, Modern JavaScript, Web Application Architecture, Data Visualization, Optical Character Recognition (OCR), Error Handling, Software Design, Figma to React, Deployment, API Development, Dashboards, Web Dashboards, Azure, RESTFul APIs, JSON, Healthcare, OAuth, Clean Architecture, Quality Assurance (QA), UI Components
Lead Software Engineer
2025 - 2025
Jannik Sinner Foundation
- Developed a high-performance, responsive website from the ground up using Next.js and TypeScript, successfully translating complex graphic designs into a functional Server-Side Rendered (SSR) platform.
- Architected and managed the full deployment lifecycle on Vercel, ensuring 99.9% uptime and optimal global delivery for the foundation's launch.
- Engineered an automated CI/CD pipeline using GitHub Actions, which streamlined code integration and reduced deployment manual overhead by automating testing and staging workflows.
- Optimized the platform's SEO strategy and Core Web Vitals, resulting in faster page load times and increased discoverability for the foundation's mission-driven content.
- Implemented a scalable front-end architecture using React and Next.js, providing the foundation for a robust digital presence capable of handling high-traffic spikes during global media events.
Technologies: TypeScript, React, Vercel, GitHub Actions, Next.js, Testing, Page Speed Optimization, Pixel Perfect, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, Responsive Web Design (RWD), Video Streaming, Web Development, Node.js, Consumer-facing Products, Modern JavaScript, Error Handling, Software Design, Deployment, Video Processing
Senior Software Engineer
2024 - 2025
On
- Engineered a suite of event-driven TypeScript microservices to integrate EDI providers and marketplace partners with the Microsoft Dynamics 365 ERP system, automating sales order, shipment, and inventory synchronization.
- Architected and deployed a CI/CD pipeline that transformed the release cycle from several months to minutes, significantly increasing the frequency of production deployments and overall agility.
- Redesigned the ERP integration middleware architecture using REST APIs and event-driven pipelines, reducing system error rates and enhancing observability across the Dynamics 365 data integration layer.
- Standardized technical excellence by defining new REST API protocols and implementing strict TypeScript configurations (ESLint/Strict Mode), resulting in improved code maintainability and a 30% reduction in technical debt.
- Modernized the legacy tech stack and led Scrum ceremonies, facilitating cross-functional communication between stakeholders and system owners to ensure seamless integration of new standards.
Technologies: Node.js, TypeScript, TypeORM, Kubernetes, Azure, Serverless Architecture, MySQL, PostgreSQL, Microsoft Dynamics 365, Rithum, NestJS, Azure Serverless Functions, Azure Service Bus, Microsoft SQL Server, Jest, EDIFACT, Salsify, GitHub Actions, Testing, API Integration, SST, Data Integration, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, QA Automation, API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, APIs, Solution Architecture, Cloud, Modern JavaScript, Refactoring, Web Application Architecture, Microservices, OpenAPI, Swagger, Telemetry, Error Handling, Amazon Web Services (AWS), AWS Lambda, SQL, Event-driven Architecture, Event-driven Systems, Terraform, Containerization, Software Design, High-availability Systems, Deployment, API Development, Dashboards, Database Architecture, Object Storage, Web Dashboards, RESTFul APIs, Apache Kafka, Data Processing Automation, Document Parsing, JSON, Automation, Data Pipelines, Data Transformation, Third-party APIs, Webhooks, Cron, Back-end, Clean Architecture, Middleware, Repository Pattern, Legacy Code, Migration, Database Migration, Quality Assurance (QA), Cloud Infrastructure, Database Design, Enterprise Resource Planning (ERP), ERP Implementation
Lead Software Engineer
2024 - 2024
Checkatrade
- Built back-end microservices, formulating the core platform for the new Checkatrade end-to-end offering.
- Designed API standards and a set of REST and AsyncAPI.
- Converted user stories into technical requirements.
- Communicated with all stakeholders and legacy system owners.
- Introduced shared types and SDK packages to speed up the cross-team development process, increase code re-usage, decrease code duplication, and improve overall quality.
- Delivered beta and MVP apps on time despite ultra-tight deadlines.
Technologies: Node.js, TypeScript, TypeORM, Express.js, Fastify, PostgreSQL, Google Cloud Platform (GCP), Pub/Sub, GitHub Actions, Terraform, Helm, Firebase, OpenID Connect (OIDC), JSON Web Tokens (JWT), Docker, Jest, Datadog, GetStream, RDBMS, IT Project Management, Software Engineering, Google Cloud SQL, E2E Testing, ESLint, Prometheus, Winston, REST APIs, Google Pub/Sub, UML, Ubuntu, NPM, GitHub, OAuth 2, Architecture, Cloud Architecture, Scalability, Web Scalability, ECMAScript (ES6), CI/CD Pipelines, DevOps, Security, Testing, API Integration, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Redis, QA Automation, API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Stripe API, Payment Processing, Web Development, APIs, Fintech, Payments, iOS, Project Management, React Native, Solution Architecture, Cloud, Zod, Zod Schema, Consumer-facing Products, Modern JavaScript, Refactoring, Web Application Architecture, Microservices, Technical Leadership, OpenAPI, Swagger, Telemetry, Error Handling, SQL, Event-driven Architecture, Event-driven Systems, Containerization, Software Design, High-availability Systems, Payment APIs, Deployment, API Development, Database Architecture, Web Dashboards, API Gateways, RESTFul APIs, Apache Kafka, JSON, Webhooks, Back-end, OAuth, Clean Architecture, Domain-driven Design (DDD), Middleware, Repository Pattern, Dependency Injection, Legacy Code, Migration, Database Migration, Quality Assurance (QA), Cloud Infrastructure, Database Design
Senior Software Engineer
2020 - 2023
Engel & Völkers
- Built a single-page application managing contracts and licensing fees.
- Implemented continuous integration and continuous delivery processes using GitLab.
- Built a REST API using Node.js, TypeScript, and PostgreSQL back end, deployed with Docker to a Kubernetes cluster on GCP.
- Hired new team members and supervised less experienced developers.
- Converted business requirements into user stories and software architecture.
- Designed and implemented the product's authentication and authorization system from scratch, including role-based access control (RBAC), user identity, and session management.
Technologies: TypeORM, TypeScript, PostgreSQL, SCSS, Kubernetes, React, Keycloak, Grafana, Koa, REST APIs, Terraform, Google Pub/Sub, Winston, Prometheus, SAP Business ByDesign, SAP, Mailgun, Sentry, Jest, Cypress, ESLint, Material UI, Formik, Redux, i18n, Yup, React-Intl, Webpack, E2E Testing, Docker, Google Cloud Platform (GCP), Google Cloud Storage, Google Cloud SQL, GitLab CI/CD, GitLab, Kanban, Scrum, Software Architecture, Cloud Architecture, B2B, Engineering, Architecture, Leadership, Full-stack, Agile, Requirements Analysis, Authentication, SDKs, Front-end Architecture, Front-end Design, Back-end Development, Web Security, LDAP, Helm, Pub/Sub, RDBMS, IT Project Management, Software Engineering, Ubuntu, NPM, OAuth 2, Playwright, React Testing Library, Web Scalability, ECMAScript (ES6), CI/CD Pipelines, DevOps, Security, Chrome DevTools, Testing, Pixel Perfect, API Integration, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Redis, Multi-tenant SaaS, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, Node.js, APIs, Solution Architecture, Cloud, React Redux, Modern JavaScript, Refactoring, Web Application Architecture, Microservices, OpenAPI, Swagger, Error Handling, SQL, Event-driven Architecture, Event-driven Systems, Containerization, Software Design, High-availability Systems, Row-level Security (RLS), Figma to React, Automations, API Development, Dashboards, Database Architecture, Object Storage, Role-based Access Control (RBAC), Web Dashboards, API Gateways, RESTFul APIs, Document Parsing, Financial Data, JSON, UI Design, Automation, Data Pipelines, Third-party APIs, Webhooks, Cron, Back-end, OAuth, Clean Architecture, Domain-driven Design (DDD), Middleware, Repository Pattern, Legacy Code, Migration, Database Migration, Quality Assurance (QA), Cloud Infrastructure, Database Design, UI Components
Software Architect
2020 - 2020
Coperniq
- Advised on the software architecture for an MVP project management tool for solar engineering companies.
- Provided consulting services on choosing appropriate technologies and tools.
- Hired new engineers, built the team, and set up processes to deliver the project efficiently.
Technologies: React, Node.js, Express.js, MongoDB, TypeScript, Software Architecture, Project Consultancy, B2B, Engineering, Architecture, Leadership, Full-stack, Agile, Requirements Analysis, RDBMS, Software Engineering, REST APIs, GitHub, Security, Startups, API Integration, Multi-tenant SaaS, API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, APIs, Solution Architecture, Cloud, Modern JavaScript, Web Application Architecture, Technical Leadership, OpenAPI, Swagger, Error Handling, Containerization, Software Design, API Development, Database Architecture, Role-based Access Control (RBAC), RESTFul APIs, Third-party APIs, Back-end, Clean Architecture, Early-stage Startups
Senior Software Engineer
2020 - 2020
InterJoin Ltd
- Played a key role in InterJoin, a startup in the seed phase that was building an online platform to connect people interested in exchanging knowledge and services.
- Built the MVP prototype rapidly from scratch based on the Zeplin designs.
- Developed a single-page application in React using the Next.js framework, partially rendered statically and server-side for SEO optimization.
- Constructed a Node.js back end in TypeScript for the app using MongoDB as a database.
- Integrated a few open APIs for mocking parts of the profile, such as photos, to satisfy the MVP concept in the given limited time.
- Created continuous deployment pipelines using Vercel.
- Advised on UX and UI proposals from the designer who was part of the team.
Technologies: Vercel, MongoDB, Koa, Node.js, TypeScript, Next.js, Redux, React, Serverless, JavaScript, Full-stack Development, Front-end Development, Git, CSS, HTML, Front-end, Web Applications, APIs, User Experience (UX), User Interface (UI), Software Architecture, Project Consultancy, Cloud Architecture, Engineering, Architecture, Leadership, Full-stack, Agile, Requirements Analysis, Authentication, Front-end Architecture, Front-end Design, Back-end Development, RDBMS, Software Engineering, ESLint, Winston, REST APIs, Ubuntu, NPM, GitHub, OAuth 2, SSG, Server-side Rendering (SSR), Static Site Generators, Web Performance Optimization (WPO), ECMAScript (ES6), GraphQL, CI/CD Pipelines, Startups, Chrome DevTools, Pixel Perfect, API Integration, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, Responsive Web Design (RWD), Mobile First, API Architecture, Databases, SaaS, Software System Architecture Development, System Architecture, Web Development, Cloud, React Redux, Consumer-facing Products, Modern JavaScript, Web Application Architecture, Error Handling, Software Design, Figma to React, API Development, Database Architecture, Object Storage, Back-end, OAuth, Clean Architecture, Database Migration, Database Design, Early-stage Startups
Lead Software Engineer
2020 - 2020
COMATCH
- Contributed significantly to an online marketplace that connects companies of all sizes with independent business consultants and industry experts registered in their network for project-based work.
- Built a microservice using TypeScript, which extracts and analyzes text from CVs exported from LinkedIn in PDF format and converts them to machine-readable JSON.
- Established continuous integration processes using CircleCI.
- Configured the deployment using AWS API Gateway and Lambda.
- Led a small team of two back-end software engineers.
Technologies: AWS Lambda, Amazon API Gateway, Amazon S3 (AWS S3), Jest, Koa, Node.js, TypeScript, Serverless, JavaScript, Test-driven Development (TDD), Git, Unit Testing, APIs, Software Architecture, Engineering, Architecture, Leadership, Agile, Back-end Development, PDF, Software Engineering, E2E Testing, ESLint, REST APIs, Ubuntu, NPM, GitHub, OAuth 2, ECMAScript (ES6), CI/CD Pipelines, Security, Testing, API Integration, General Data Protection Regulation (GDPR), Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, QA Automation, API Architecture, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, Solution Architecture, Cloud, Modern JavaScript, Web Application Architecture, Microservices, Technical Leadership, OpenAPI, Swagger, Error Handling, Amazon Web Services (AWS), Software Design, Deployment, API Development, Object Storage, RESTFul APIs, Data Processing Automation, Document Parsing, JSON, Automation, Data Transformation, CRM APIs, Back-end, Clean Architecture, Quality Assurance (QA), Cloud Infrastructure, Rule-based Programming
Senior Software Engineer
2019 - 2020
Zalando Lounge Service
- Worked on a Salesforce integration and a content management application for ordering content from agencies.
- Developed various tools supporting marketing activities and data analytics for the marketing tech department.
- Built a single-page application in React, with a Node.js, TypeScript, and PostgreSQL back end, to optimize the process of managing content orders from external agencies, such as product descriptions, landing pages, and SEO.
- Integrated with the agency's 3rd-party APIs and exposed my own API as a webhook to receive agency process notifications.
- Created a service for downloading analytical data daily from App Store Connect, converting it to CSV, and exposing it to the data analytics team in the S3 bucket.
- Developed mass marketing emails using Salesforce Marketing Cloud.
- Handled the deployments and infrastructure management in AWS with Kubernetes.
Technologies: Amazon Web Services (AWS), HTML5, CSS, HTML Email, JavaScript, Salesforce Marketing Cloud, Kubernetes, Docker, PostgreSQL, Node.js, TypeScript, React, Full-stack Development, eCommerce, Front-end Development, Git, HTML, Front-end, Web Applications, Unit Testing, User Experience (UX), User Interface (UI), Engineering, Full-stack, Agile, Back-end Development, Large-scale Projects, RDBMS, Software Engineering, ESLint, Winston, REST APIs, Salesforce, Ubuntu, NPM, GitHub, Gatsby, Puppeteer, Customer Relationship Management (CRM), SSG, Scalability, Search Engine Optimization (SEO), Server-side Rendering (SSR), Static Site Generators, Web Performance Optimization (WPO), Web Scalability, ECMAScript (ES6), GraphQL, CI/CD Pipelines, Chrome DevTools, Testing, API Integration, Salesforce API, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, SaaS, Software System Architecture Development, Web Development, APIs, iOS, Cloud, React Redux, Consumer-facing Products, Modern JavaScript, Refactoring, Web Application Architecture, Microservices, Error Handling, SQL, Containerization, Software Design, Figma to React, API Development, Database Architecture, Object Storage, Role-based Access Control (RBAC), RESTFul APIs, JSON, Third-party APIs, Back-end, Clean Architecture, Domain-driven Design (DDD), Legacy Code, Database Migration, Quality Assurance (QA), CRM, Cloud Infrastructure, Database Design, UI Components, Contentful
Senior Software Engineer
2019 - 2019
Daimler Fleetboard
- Worked on a platform for tracking the geopositioning and truck-trailer coupling status using a mobile app and physical sensors combined with data science algorithms.
- Built a Node.js back end collecting data from various sources, including a mobile app, SOAP Listener, and Azure Event Hubs, persisting it to PostgreSQL and forwarding it to a data science platform.
- Developed a single-page application in Angular 8, displaying the geopositioning and coupling status over the HERE Maps view.
- Handled the deployments and infrastructure management in Azure DevOps and Azure with Kubernetes.
Technologies: Azure DevOps, Azure, Kubernetes, Docker, TypeORM, PostgreSQL, Koa, Node.js, TypeScript, RxJS, NgRx, Angular, JavaScript, Full-stack Development, SQL, Front-end Development, Git, CSS, HTML, Front-end, Web Applications, Unit Testing, APIs, User Interface (UI), Software Architecture, B2B, Engineering, Full-stack, Agile, Authentication, Front-end Architecture, Front-end Design, Back-end Development, Web Security, Maps, RDBMS, Software Engineering, E2E Testing, ESLint, Winston, REST APIs, Ubuntu, NPM, OAuth 2, ECMAScript (ES6), CI/CD Pipelines, Startups, Chrome DevTools, Testing, Pixel Perfect, API Integration, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Multi-tenant SaaS, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, Cloud, Modern JavaScript, Refactoring, Web Application Architecture, Data Visualization, GIS, Microservices, Internet of Things (IoT), MQTT, Sockets, Telemetry, Error Handling, Event-driven Architecture, Event-driven Systems, Containerization, Software Design, High-availability Systems, Figma to React, API Development, Dashboards, Database Architecture, Role-based Access Control (RBAC), RESTFul APIs, JSON, Webhooks, Back-end, OAuth, Clean Architecture, Database Migration, Quality Assurance (QA), Cloud Infrastructure, Database Design, UI Components, Real-time Data
Front-end Lead
2018 - 2019
Körber Digital
- Led a team of four front-end engineers working on an IoT product.
- Built single-page applications in React that displayed analytical data for a production line and enabled operators to send feedback for machine speed losses.
- Developed the back end in JavaScript-based serverless architecture on AWS.
- Managed deployments and infrastructure in CircleCI and AWS or Azure.
- Hired new team members, including front-end, back-end, and QA engineers.
Technologies: Amazon Web Services (AWS), Sentry, CircleCI, Azure, Enzyme, Mocha, Jest, Node.js, D3.js, Redux, React, Serverless, JavaScript, Test-driven Development (TDD), CTO, Front-end Development, Git, CSS, HTML, Front-end, Web Applications, Unit Testing, User Experience (UX), User Interface (UI), Software Architecture, Cloud Architecture, B2B, Engineering, Architecture, Leadership, Full-stack, Agile, Requirements Analysis, Authentication, SDKs, Front-end Architecture, Front-end Design, Web Security, RDBMS, Software Engineering, E2E Testing, i18n, ESLint, REST APIs, Ubuntu, NPM, GitHub, OAuth 2, Storybook, Serverless Architecture, WebSockets, SSG, Scalability, Server-side Rendering (SSR), Web Performance Optimization (WPO), Web Scalability, ECMAScript (ES6), Lazy Loading, Accessibility, CI/CD Pipelines, Security, Startups, Web Accessibility, Chrome DevTools, AWS IoT, Testing, Pixel Perfect, API Integration, SST, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Amazon RDS, Multi-tenant SaaS, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, APIs, Solution Architecture, Cloud, React Redux, Modern JavaScript, Web Application Architecture, Data Visualization, Microservices, Technical Leadership, Internet of Things (IoT), MQTT, Sockets, Telemetry, Robotics, Error Handling, AWS Lambda, Event-driven Architecture, Event-driven Systems, Software Design, High-availability Systems, Amazon Simple Queue Service (SQS), Figma to React, Deployment, API Development, Dashboards, Database Architecture, Role-based Access Control (RBAC), Web Dashboards, API Gateways, RESTFul APIs, JSON, Data Pipelines, Data Transformation, Webhooks, Back-end, OAuth, Clean Architecture, Quality Assurance (QA), Cloud Infrastructure, Early-stage Startups, UI Components, Real-time Data
Senior Software Engineer
2017 - 2018
GoEuro (now Omio)
- Contributed as part of the fast integrations department for GoEuro, a travel metasearch engine that allows users to compare the price and journey time of air, rail, and bus travel options in a single search.
- Built end-to-end services offered to micro providers, covering search, routing, booking, ticket generation, and sales reporting.
- Developed back-end services in Node.js, including search, routing, and booking, which I implemented in a microservice architecture and deployed to GCP using Kubernetes.
- Implemented a PDF ticket-printing service as a server-side React app in Node.js.
- Managed deployments and infrastructure in Kubernetes.
Technologies: Sentry, Kibana, Kubernetes, Docker, GIS, MongoDB, Protobuf, Node.js, React, JavaScript, SQL, Git, HTML, Unit Testing, APIs, Software Architecture, Engineering, Architecture, Agile, Requirements Analysis, SDKs, Back-end Development, PDF, Large-scale Projects, Web Security, Routing, Maps, RDBMS, Software Engineering, E2E Testing, ESLint, REST APIs, Ubuntu, NPM, GitHub, Travis CI, SSG, Scalability, Server-side Rendering (SSR), Web Scalability, ECMAScript (ES6), Caching, CI/CD Pipelines, Security, Startups, Testing, API Integration, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, QA Automation, API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, Solution Architecture, Cloud, Consumer-facing Products, Modern JavaScript, Refactoring, Web Application Architecture, Microservices, Telemetry, Error Handling, Containerization, Software Design, High-availability Systems, API Development, Database Architecture, Object Storage, RESTFul APIs, JSON, Third-party APIs, Webhooks, Back-end, Clean Architecture, Domain-driven Design (DDD), Legacy Code, Quality Assurance (QA), Cloud Infrastructure
Senior Software Engineer
2017 - 2017
SatoshiPay
- Built a drop-in web widget serving as a payment and content management client using React and Redux.
- Migrated from Bitcoin to alternative cryptocurrency providers.
- Implemented new cryptocurrency micropayment services.
Technologies: Cryptocurrency, IOTA, Stellar SDK, Bitcoin, Docker Cloud, Docker, Sinon.JS, Chai, Mocha, Karma, MongoDB, Node.js, Redux, React, JavaScript, Full-stack Development, Front-end Development, Git, CSS, HTML, Front-end, Web Applications, Unit Testing, Cryptography, User Interface (UI), eCommerce, Engineering, Full-stack, Agile, SDKs, Web Security, Software Engineering, E2E Testing, ESLint, REST APIs, NPM, GitHub, ECMAScript (ES6), Security, Startups, Chrome DevTools, Testing, Pixel Perfect, API Integration, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), Mobile First, Databases, SaaS, Software System Architecture Development, System Architecture, Stripe API, Payment Processing, Web Development, APIs, Fintech, Payments, Cloud, React Redux, Consumer-facing Products, Modern JavaScript, Refactoring, Web Application Architecture, Error Handling, Software Design, Payment APIs, API Development, Database Architecture, RESTFul APIs, Financial Data, JSON, Third-party APIs, Back-end, Quality Assurance (QA), Cloud Infrastructure, Database Design
Senior Software Engineer | Product Owner
2016 - 2017
Freelance
- Served as a senior software engineer at SwapDoq and product owner at TravelMind Inc.
- Built from scratch a prototype of a mobile web app based on React for sharing content-rich marketing brochures that include photos, videos, 3D objects, and animations.
- Researched and designed a prototype of a next-generation travel management mobile app providing a seamless booking and time organization experience with a slick and simple user interface.
Technologies: SCSS, HTML5, React, JavaScript, Front-end Development, Git, CSS, HTML, Front-end, Web Applications, Unit Testing, User Interface (UI), User Experience (UX), Software Architecture, Project Consultancy, Engineering, Agile, Requirements Analysis, Front-end Architecture, Software Engineering, ESLint, NPM, GitHub, InVision, Certified Scrum Product Owner (CSPO), IT Project Management, API Integration, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Documentation, Software System Architecture Development, Web Development, Web Application Architecture, Error Handling
Senior Software Engineer
2016 - 2017
Zalando
- Developed Zalando's shop, the main front-end application customers use among many applications and services.
- Built a React component library used across the company to quickly develop new features and maintain consistent UX/UI.
- Applied refreshed UI designs for the main parts of the shopping application.
Technologies: Zeplin, Java, Jakarta Server Pages (JSP), Less, CSS3, HTML5, Sinon.JS, Enzyme, Chai, Mocha, Webpack, React, JavaScript, Test-driven Development (TDD), eCommerce, Front-end Development, Git, CSS, HTML, Front-end, Web Applications, Unit Testing, User Interface (UI), Engineering, Agile, Technical Writing, SDK Development, SDKs, Front-end Architecture, Front-end Design, Large-scale Projects, Software Engineering, ESLint, REST APIs, NPM, Scalability, Lazy Loading, Chrome DevTools, Testing, Page Speed Optimization, Pixel Perfect, API Integration, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, QA Automation, Documentation, Web Development, APIs, Cloud, Consumer-facing Products, Modern JavaScript, Refactoring, Web Application Architecture, Microservices, Error Handling, Software Design, RESTFul APIs, Legacy Code, Migration, Quality Assurance (QA), UI Components
Senior Product Owner
2015 - 2016
Smartlaw (owned by Wolters Kluwer)
- Developed new product ideas to increase the user base.
- Refactored an existing functionality to increase conversions.
- Implemented a notification system to bring people back to the site more often.
- Redesigned and improved interactions for a better user experience and increased satisfaction.
- Managed the backlog and prioritized features and bug fixes.
Technologies: Moqups, InVision, Jira, Web Applications, User Experience (UX), Software Development Management, Engineering, Agile Project Management, Agile, Front-end Design, Certified Scrum Product Owner (CSPO), IT Project Management, REST APIs, A/B Testing, Startups, General Data Protection Regulation (GDPR), Legal, White Box Testing, Documentation, SaaS, Web Development, APIs, Project Management, Cloud, Consumer-facing Products, Role-based Access Control (RBAC), RESTFul APIs, Document Parsing
Senior Front-end Software Engineer
2015 - 2015
smava
- Developed a front-end application using Backbone.js.
- Refactored existing code to achieve greater readability, testability, and performance.
- Converted parts of the site to support responsive design.
- Solved compatibility issues between browsers and platforms.
Technologies: Java, Sass, CSS3, HTML5, jQuery, Backbone.js, JavaScript, Front-end Development, Git, CSS, HTML, Front-end, Web Applications, Unit Testing, User Interface (UI), Engineering, Agile, Front-end Architecture, Front-end Design, Software Engineering, Search Engine Optimization (SEO), Chrome DevTools, Page Speed Optimization, Pixel Perfect, API Integration, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), SaaS, Web Development, APIs, Fintech, Cloud, Consumer-facing Products, Refactoring, Web Application Architecture, Error Handling, Software Design, RESTFul APIs, Financial Data, JSON, Legacy Code
Product Owner | Technical Lead – Izumi
2012 - 2015
Here Technologies (formerly a Nokia business)
- Worked on Izumi, an internal crowdsourcing localization tool used by the HERE product family, moving the localization process into the continuous delivery world and shortening translation cycles from three weeks to a few minutes.
- Defined the product scope and technical architecture.
- Managed a small development team in Berlin, Germany, and Atlanta, USA.
- Developed a full stack in Ruby on Rails with MySQL, HTML5, Sass, and JavaScript.
- Introduced crowdsourced localization to the company.
- Changed the localization process from a highly manual job to a fully automated process.
- Shortened localization cycles from a few weeks to a few minutes.
Technologies: Amazon Web Services (AWS), Object-oriented JavaScript (OOJS), Kanban, Jira, Amazon Route 53, Amazon, Amazon EC2, Amazon CloudFront CDN, Redis, Amazon S3 (AWS S3), jQuery, Bootstrap, Sass, CSS3, HTML5, MySQL, Ruby on Rails (RoR), Ruby, JavaScript, Full-stack Development, SQL, Front-end Development, Git, CSS, HTML, Front-end, Web Applications, Unit Testing, APIs, User Experience (UX), User Interface (UI), Software Architecture, Software Development Management, Cloud Architecture, B2B, Engineering, People Management, Team Management, Agile Project Management, Architecture, Leadership, Agile, Requirements Analysis, Authentication, Technical Writing, SDK Development, SDKs, Front-end Architecture, Front-end Design, Back-end Development, Web Security, Certified Scrum Product Owner (CSPO), Lean Project Management, RDBMS, IT Project Management, Software Engineering, i18n, REST APIs, Startups, Chrome DevTools, Pixel Perfect, API Integration, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, Project Management, Solution Architecture, Cloud, Consumer-facing Products, Web Application Architecture, Microservices, Technical Leadership, Error Handling, Amazon CloudWatch, Software Design, API Development, Dashboards, Database Architecture, Role-based Access Control (RBAC), Web Dashboards, RESTFul APIs, JSON, UI Design, SendGrid, Back-end, Clean Architecture, Database Migration, Quality Assurance (QA), Database Design, Early-stage Startups
Product Owner | Technical Lead – Dashboard
2011 - 2012
Here Technologies (formerly a Nokia business)
- Developed the analytics dashboard displaying major KPIs for various Nokia products and services.
- Handled product definition, design, and development.
- Led the development and delivery team of three engineers.
- Increased team engagement significantly and improved work quality and results by applying my expertise in product KPIs.
Technologies: Object-oriented JavaScript (OOJS), Kanban, Jira, jQuery, CSS3, HTML5, MySQL, Grails, JavaScript, Full-stack Development, Front-end Development, Git, CSS, HTML, Front-end, Web Applications, Unit Testing, User Experience (UX), User Interface (UI), Software Architecture, Software Development Management, Cloud Architecture, B2B, Engineering, People Management, Team Management, Agile Project Management, Architecture, Leadership, Agile, Requirements Analysis, Authentication, Front-end Architecture, Front-end Design, Back-end Development, Certified Scrum Product Owner (CSPO), Lean Project Management, RDBMS, IT Project Management, Software Engineering, REST APIs, Cucumber, Startups, Chrome DevTools, Pixel Perfect, API Integration, Automated Testing, White Box Testing, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, APIs, Project Management, Solution Architecture, Cloud, Consumer-facing Products, Web Application Architecture, Data Visualization, Microservices, Technical Leadership, Telemetry, Error Handling, Amazon Web Services (AWS), SQL, Amazon CloudWatch, Software Design, API Development, Dashboards, Database Architecture, Role-based Access Control (RBAC), Web Dashboards, RESTFul APIs, JSON, UI Design, Back-end, Clean Architecture, Database Migration, Quality Assurance (QA), Database Design, Early-stage Startups
Senior Development Manager
2009 - 2012
Here Technologies (formerly a Nokia business)
- Enhanced front-end performance by reducing the web page loading time from 30 to less than six seconds.
- Improved cross-team cooperation by implementing continuous integration processes and running weekly tech talks, where developers could freely exchange knowledge.
- Optimized the build system and overall release process—from every few months to only three weeks. Shortened the time from development to release by deploying it to production at the end of each sprint.
- Increased Google indexing from thousands to millions of pages by designing and implementing an SEO strategy to boost presence on Google.
- Mentored a web front-end development team of 28 developers.
- Oversaw the overall Nokia Maps architecture for the web.
- Led the integration with other Nokia and HERE services.
- Worked on new product development and ideas with business owners and the UX team.
Technologies: Apache Tomcat, Jetty, Object-oriented JavaScript (OOJS), JUnit, Jasmine, JBehave, Selenium, Hudson, Nexus, Apache Maven, Java, CSS3, HTML5, CTO, Web Applications, Software Architecture, Software Development Management, Cloud Architecture, Engineering, Delivery Management, Engineering Management, People Management, Team Management, Agile Project Management, Architecture, Leadership, Full-stack, Agile, Requirements Analysis, Technical Writing, SDK Development, SDKs, Front-end Architecture, Large-scale Projects, Maps, Lean Project Management, IT Project Management, Software Engineering, i18n, REST APIs, Scalability, Web Performance Optimization (WPO), Web Scalability, A/B Testing, WebPageTest, Chrome DevTools, Page Speed Optimization, API Integration, White Box Testing, Cross-browser Compatibility, QA Automation, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, APIs, Project Management, Solution Architecture, Cloud, Consumer-facing Products, Refactoring, Web Application Architecture, GIS, Microservices, Technical Leadership, OpenAPI, Swagger, Telemetry, Error Handling, Amazon Web Services (AWS), SQL, Amazon CloudWatch, Software Design, API Development, RESTFul APIs, JSON, Back-end, Clean Architecture, Domain-driven Design (DDD), Legacy Code
Development Manager
2007 - 2009
Wayn
- Hired and managed a development team of 12 developers and three testers, helping build the Polish branch office's unique, friendly atmosphere.
- Managed the workflow to maintain a dynamic development process, ensuring the website's quick growth.
- Authored most of the website's core back-end mechanisms and provided expertise in database optimization.
- Led the development process and wrote the most crucial part of the system.
Technologies: Transact-SQL (T-SQL), Microsoft SQL Server, Visual Basic 6 (VB6), CSS, JavaScript, HTML, SQL, CTO, Web Applications, User Experience (UX), Software Architecture, Software Development Management, Engineering, Engineering Management, People Management, Team Management, Agile Project Management, Architecture, Leadership, Full-stack, Agile, Requirements Analysis, Authentication, Front-end Architecture, Back-end Development, Large-scale Projects, Web Security, Lean Project Management, RDBMS, IT Project Management, Software Engineering, Mailgun, REST APIs, Scraping, Scalability, Search Engine Optimization (SEO), Web Performance Optimization (WPO), Web Scalability, Lazy Loading, Caching, A/B Testing, Security, Startups, WebPageTest, Page Speed Optimization, API Integration, White Box Testing, Cross-browser Compatibility, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Video Streaming, Web Development, APIs, Project Management, Consumer-facing Products, Refactoring, Web Application Architecture, Technical Leadership, Error Handling, Software Design, High-availability Systems, Website Data Scraping, API Development, Database Architecture, Role-based Access Control (RBAC), RESTFul APIs, JSON, Third-party APIs, Back-end, Clean Architecture, Database Migration, Database Design, Early-stage Startups
Director of Research and Development
2007 - 2009
Wayn
- Solved the crucial performance issues of the website by clustering the back-end database.
- Improved the core template processing mechanism, which sped up the development process.
- Prepared the website for a multilingual interface.
- Increased website traffic significantly by redesigning the website interface, which company members and the industry warmly welcomed.
- Hired and led a development team of 16 developers and seven testers and an R&D team of two application architects and three graphic designers.
- Mentored and helped individuals to achieve their goals.
- Worked with partners on various product integrations, including global SIM cards, geolocation service, white labeling, branded credit cards, and hotel or restaurant booking.
Technologies: Transact-SQL (T-SQL), Microsoft SQL Server, Visual Basic 6 (VB6), CSS, JavaScript, HTML, CTO, SQL, Web Applications, User Experience (UX), Software Architecture, Software Development Management, Engineering, Delivery Management, Engineering Management, People Management, Team Management, Agile Project Management, Architecture, Leadership, Agile, Requirements Analysis, Authentication, Front-end Architecture, Front-end Design, Large-scale Projects, Web Security, Certified Scrum Product Owner (CSPO), Lean Project Management, RDBMS, IT Project Management, Software Engineering, Mailgun, REST APIs, Scalability, Search Engine Optimization (SEO), Web Performance Optimization (WPO), Web Scalability, Lazy Loading, Caching, A/B Testing, Security, Startups, WebPageTest, Page Speed Optimization, API Integration, White Box Testing, Cross-browser Compatibility, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Video Streaming, Web Development, APIs, Project Management, Solution Architecture, Consumer-facing Products, Refactoring, Web Application Architecture, Technical Leadership, Error Handling, Software Design, High-availability Systems, Website Data Scraping, API Development, Database Architecture, Role-based Access Control (RBAC), RESTFul APIs, JSON, UI Design, Third-party APIs, Back-end, Clean Architecture, Database Migration, Database Design, Early-stage Startups
Owner | Network Administrator
2002 - 2007
HYPODE Networks
- Started HYPODE Networks to provide part-time network administration services.
- Built and managed a local computer network infrastructure.
- Provided over 50 clients with internet access and services like email accounts and personal website hosting.
Technologies: Linux, Apache, LDAP
Senior Software Engineer | Team Leader
2005 - 2006
Mole Resourcing Ltd
- Developed the website's first version based on business owners' specifications.
- Built and managed a team of three developers and one graphic designer.
- Managed the build, deployment, and testing processes.
Technologies: MySQL, PHP, JavaScript, CSS, HTML, Engineering, RDBMS, IT Project Management, Software Engineering, REST APIs, Startups, Bug Fixes, Code Refactoring, Debugging, Consumer-facing Products, Error Handling
Senior Software Engineer
2004 - 2006
Wayn
- Joined as one of the first two developers and was a co-author of the core website mechanisms.
- Built the "invitation via contact import" mechanism, which allowed the website to grow from 45,000 to 1.5+ million members within six months and later maintain that growth.
- Developed a web-based instant messenger, written using pure HTML and JavaScript—one of the first worldwide—working almost unchanged until today.
Technologies: Transact-SQL (T-SQL), Microsoft SQL Server, Visual Basic 6 (VB6), CSS, JavaScript, HTML, Full-stack Development, SQL, Front-end Development, Front-end, Web Applications, User Interface (UI), User Experience (UX), Software Architecture, Engineering, Architecture, Leadership, Full-stack, Agile, Authentication, Front-end Architecture, Front-end Design, Back-end Development, Large-scale Projects, Web Security, RDBMS, Software Engineering, Mailgun, REST APIs, Scraping, Scalability, Search Engine Optimization (SEO), Web Performance Optimization (WPO), Web Scalability, Lazy Loading, Caching, A/B Testing, Security, Startups, WebPageTest, Page Speed Optimization, Pixel Perfect, API Integration, Web Scraping, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, SaaS, Software System Architecture Development, System Architecture, Payment Processing, Video Streaming, Web Development, APIs, Payments, Consumer-facing Products, Web Application Architecture, Error Handling, Software Design, High-availability Systems, Website Data Scraping, Scripting, API Development, Database Architecture, Role-based Access Control (RBAC), RESTFul APIs, JSON, Third-party APIs, Back-end, Clean Architecture, Database Migration, Database Design, Early-stage Startups
Senior Software Engineer
2000 - 2005
Heuthes
- Designed an advanced client-side template processing mechanism that separated the visualization layer from the data stream and business logic.
- Built the solution using advanced JavaScript and Ajax and rendered it in browsers using XML and XSL. This improved the development process and application performance via better caching and decreased data transmission requirements.
- Developed the web-based business management system using advanced JavaScript, HTML, and HDB, a scripting language invented internally by the company, written in Delphi and running on Windows and Linux.
- Prepared technical documentation in Polish and English for the web-based banking products developed by the company Filia@Web and Virtual Info Banking.
Technologies: dBASE, PostgreSQL, Delphi, XPath, XSL, XML, CSS, JavaScript, HTML, Full-stack Development, SQL, Front-end Development, Front-end, Web Applications, APIs, User Interface (UI), User Experience (UX), Software Architecture, B2B, Engineering, Architecture, Full-stack, Authentication, Front-end Architecture, Front-end Design, Back-end Development, Web Security, RDBMS, Software Engineering, REST APIs, Security, Pixel Perfect, API Integration, Bug Fixes, Code Refactoring, Debugging, Cross-browser Compatibility, Responsive Web Design (RWD), API Architecture, Databases, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Web Development, Fintech, Web Application Architecture, Error Handling, Software Design, API Development, Database Architecture, Role-based Access Control (RBAC), RESTFul APIs, Data Processing Automation, Financial Data, JSON, Data Transformation, CRM APIs, Back-end, Clean Architecture, Database Migration, Database Design
Teacher
2003 - 2004
Maius College
- Gave lectures and led laboratory classes on the subject of databases.
- Taught relational databases and SQL language based on the PostgreSQL database system.
- Engaged as a part-time teacher in the College of Economics and Information Technology while employed as a full-time teacher at Szczecin University of Technology.
Technologies: PostgreSQL, RDBMS, Pedagogy, Databases, System Architecture, Web Development, Algorithms, SQL, Database Architecture, RESTFul APIs, Third-party APIs, Database Design
Teacher
2000 - 2004
Szczecin University of Technology
- Used the modern RDBM system to teach SQL, which required organizing a dedicated server running PostgreSQL for the students' databases.
- Organized and led a group of students interested in software development. They participated in a contest for the best application written in Java for the Nokia Communicator 92xx platform organized by Borland Poland.
- Introduced HTML and JavaScript classes in the Introduction to Computer Science course.
- Taught first-year Computer Science studies to Bachelor of Science students before finishing my master's degree.
Technologies: Visual Basic for Applications (VBA), UML, PHP, JavaScript, HTML, PostgreSQL, SQL, RDBMS, Software Engineering, Pedagogy, REST APIs, Page Speed Optimization, Databases, Software System Architecture Development, System Architecture, Web Development, APIs, Algorithms, Database Architecture, RESTFul APIs, Third-party APIs, Database Design
Software Engineer | Blogger
1998 - 2002
Freelance
- Developed the 2nd version of an application for Visuell Kommunikation AB in cooperation with the product manager from Sweden.
- Fostered and maintained "Delphi in Questions & Answers"—the biggest Polish website at the time about Borland Delphi—as the creator and main contributor.
- Served as the animator of the community associated with Delphi and internet newsgroups.
Technologies: CSS, HTML, dBASE, Delphi, Engineering, Desktop, Software Engineering, JavaScript, Windows API
Project History
InterJoin Ltd
A startup in the seed phase. It provides an online platform for connecting people interested in exchanging knowledge and services. I aimed to rapidly build the MVP prototype from scratch based on the Zeplin designs.
Zalando Lounge
An online outlet offering discounted fashion and lifestyle products in 17 European markets. I worked on a Salesforce integration and a content management application for ordering content from agencies. As part of the marketing tech department, I also developed various tools supporting marketing activities and data analytics.
Daimler Fleetboard
A logistics company developing tailored digital solutions to optimize logistics processes.
I worked on a platform that tracks the geopositioning and truck-trailer coupling status using a mobile app and physical sensors combined with data science algorithms. My responsibilities included building a back end in Node.js to collect data from various sources and a single-page application in Angular to display the data over the map view.
I worked on a platform that tracks the geopositioning and truck-trailer coupling status using a mobile app and physical sensors combined with data science algorithms. My responsibilities included building a back end in Node.js to collect data from various sources and a single-page application in Angular to display the data over the map view.
Körber Digital
https://www.koerber-digital.comA spin-off from Körber AG that's focused on delivering IoT-based analytics for advanced production lines in multiple industries. I built a single-page application displaying live analytics for a production line and allowing operators to send feedback for machine speed losses.
GoEuro (now Omio)
A travel metasearch engine that allows users to compare the price and journey time of air, rail, and bus travel options in a single search. As part of the fast integrations department, I built end-to-end services offered to micro providers like small bus companies, covering search, routing, booking, ticket generation, and sales reporting.
SatoshiPay
https://www.satoshipay.ioA two-way payment platform that allows content providers to charge consumers a small fee as low as one satoshi or a fraction of a cent to read, watch, or listen to content. It also provides customers with a safe cryptocurrency wallet.
Zalando Shop
http://zalando.comAn eCommerce company maintaining a cross-platform online store that sells shoes, clothing, and other fashion items. I developed the shop's main front-end application for customers, applying refreshed UI designs for the main parts of the shop application.
Smava
https://www.smava.deAn online social lending platform that facilitates peer-to-peer lending services as well as loan comparison portal for Germany’s leading banks. Borrowers can obtain cheap online credit as a clever alternative to a bank loan with investors financing these loans directly.
Since its launch in 2007, more than 15,000 investors and 6,000 borrowers have done business with each other through the smava.de credit market, with loans totaling around €55 million in value.
Since its launch in 2007, more than 15,000 investors and 6,000 borrowers have done business with each other through the smava.de credit market, with loans totaling around €55 million in value.
SmartLaw
https://www.smartlaw.deAn online platform for generating customized legal documents in a few easy steps, backed by a strong lawyer's team and many 3rd-party law offices.
SmartLaw revolutionizes the creation of contracts and other legal documents. To deliver simple, cost-effective, and individualized documents, we combine the strengths of innovative software with expert lawyers and leaders in their fields. Each document is adapted to the user's personal needs, whether a large enterprise, small business, or private individual.
They work exclusively with top-ranked lawyers, and renowned communication designers have developed the platform's user interface and intuitive design. Data protection and security also fulfill the highest certification standards.
SmartLaw revolutionizes the creation of contracts and other legal documents. To deliver simple, cost-effective, and individualized documents, we combine the strengths of innovative software with expert lawyers and leaders in their fields. Each document is adapted to the user's personal needs, whether a large enterprise, small business, or private individual.
They work exclusively with top-ranked lawyers, and renowned communication designers have developed the platform's user interface and intuitive design. Data protection and security also fulfill the highest certification standards.
HERE Platform
https://www.here.comA web companion for a localization platform. It combines highly accurate and fresh maps with cloud technology to enable rich, real-time location experiences. It is also a major competitor of Google Maps.
WAYN.com
A lifestyle-and-travel social network with 20 million members to help people discover where to go and what to do, meet like-minded people, and share aspirations and experiences. WAYN, which stands for Where Are You Now?, was referred to at the time as the "Myspace of travel."
ISOF ERP
http://www.isof.plA web-based company management system that covered multiple services, including sales, inventory, accountancy, payroll, customer relationship management, document management (DMS), eShop, logistics, eCommerce, and task management.
COMATCH (Malt)
An online marketplace that connects companies of all sizes with independent business consultants and industry experts registered in their network for project-based work. I built a microservice extracting data from a CV exported from LinkedIn.
Ruby Version Manager
https://rvm.ioA command-line tool that allows users to easily install, manage, and work with multiple Ruby environments, from interpreters to sets of gems. It supports several operating systems and all available Ruby interpreters and versions.
Faker.js
https://fakerjs.devA trendy library with over 2.5 million downloads weekly. It is used for generating massive amounts of fake but realistic data for testing and development. It was originally written in Perl, but ports to several languages exist. I worked on the JavaScript and TypeScript versions.
Ruby Configuration
https://github.com/rubyconfig/configA widespread software library in Ruby to help developers manage environment-specific settings in an accessible and usable manner. It has over 23 million downloads and is based on YAML files with ERB syntax, inheritance, multiple environments, and support for common frameworks such as Rails, Padrino, or Sinatra.
Checkatrade Consumer App
A site that connects homeowners with approved local tradespeople. The site underwent a major shift toward end-to-end experience in a mobile app. I designed and led the implementation of the core back-end platform to deliver the new mobile experience.
Education
2003 - 2004
Postgraduate Degree in Pedagogy
Szczecin University of Technology - Szczecin, Poland
1996 - 2001
Master of Science Degree in Information Technology
Szczecin University of Technology - Szczecin, Poland
Certifications
JUNE 2014 - PRESENT
The Enterprise Lean Startup Survival Guide
Udemy
NOVEMBER 2013 - PRESENT
Certified Scrum Product Owner
Scrum Alliance
Skills
Libraries/APIs
jQuery, React, Node.js, React-Intl, Chai, REST APIs, Zod, Zod Schema, React Redux, OpenAPI, API Development, Puppeteer, D3.js, Yup, Playwright, React Testing Library, Salesforce API, Stripe API, Sockets, Socket.IO, OpenAI API, Backbone.js, Windows API, Sinon.JS, NgRx, RxJS, Protobuf, Winston, Formik, Mantine, Recharts, Stripe, Firebase Web SDK
Tools
NPM, Webpack, GitHub, Git, Jira, CircleCI, Travis CI, Sentry, Terraform, GitLab CI/CD, GitLab, WebPageTest, Claude Code, n8n, Amazon CloudWatch, SendGrid, Cron, GIS, Cucumber, Salesforce Marketing Cloud, Keycloak, Grafana, Claude, MQTT, Amazon Simple Queue Service (SQS), InVision, Moqups, Amazon CloudFront CDN, Apache Maven, Hudson, Jetty, Apache Tomcat, Apache, Mocha, Zeplin, Karma, Stellar SDK, Kibana, Helm, GetStream, Litmus, TanStack Router, React Email, Amazon Simple Email Service (SES), OpenTofu, Nx, Amazon Elastic Container Service (ECS), Vitest, Astro
Languages
Object-oriented JavaScript (OOJS), HTML, CSS, Visual Basic 6 (VB6), XML, HTML5, CSS3, JavaScript, Sass, TypeScript, SCSS, SQL, Bash, ECMAScript (ES6), Modern JavaScript, Ruby, Transact-SQL (T-SQL), GraphQL, Python, Java, PHP, Delphi, dBASE, UML, Visual Basic for Applications (VBA), XSL, XPath, Less, C++, Python 3, Go
Frameworks
Next.js, Redux, Jest, Koa, Express.js, JSON Web Tokens (JWT), OAuth 2, Cypress, Fastify, SST, Swagger, Ruby on Rails (RoR), Selenium, Material UI, NestJS, Tailwind CSS, React Native, Bootstrap, Grails, JBehave, Jasmine, JUnit, Jakarta Server Pages (JSP), Angular
Paradigms
Serverless Architecture, Scrum, Kanban, Test-driven Development (TDD), Unit Testing, E2E Testing, B2B, Agile Project Management, Agile, Requirements Analysis, Search Engine Optimization (SEO), Web Performance Optimization (WPO), Testing, Automated Testing, Code Refactoring, Responsive Web Design (RWD), API Architecture, Refactoring, Web Application Architecture, Microservices, Event-driven Architecture, Role-based Access Control (RBAC), Automation, Clean Architecture, Dependency Injection, Database Design, DevOps, UI Design, Rule-based Programming, Azure DevOps, HIPAA Compliance
Platforms
Vercel, Amazon Web Services (AWS), Azure, Docker, AWS Lambda, Contentful, Salesforce, Amazon EC2, Ubuntu, Linux, Kubernetes, Google Cloud Platform (GCP), AWS IoT, Replit, Apache Kafka, Amazon, Nexus, Mailgun, Desktop, Firebase, Blockchain, Microsoft Dynamics 365, Salsify, iOS, Android
Storage
Redis, MySQL, PostgreSQL, Google Cloud Storage, Google Cloud SQL, RDBMS, SQL Server Reporting Services (SSRS), Data Integration, Databases, Database Architecture, Object Storage, JSON, Data Pipelines, Database Migration, Microsoft SQL Server, Amazon S3 (AWS S3), MongoDB, Docker Cloud, Datadog
Industry Expertise
Project Management, Healthcare
Other
Serverless, Scraping, Cloud Architecture, TypeORM, CSS Modules, Storybook, Full-stack Development, CTO, Front-end Development, Front-end, Web Applications, APIs, User Experience (UX), User Interface (UI), Google Pub/Sub, ESLint, i18n, IT Project Management, Computer Science, Software Architecture, Lean Project Management, Project Consultancy, Certified Scrum Product Owner (CSPO), Software Development Management, Engineering, Delivery Management, Engineering Management, People Management, Team Management, Architecture, Leadership, Full-stack, Authentication, SDK Development, SDKs, Front-end Architecture, Front-end Design, Back-end Development, Large-scale Projects, Pub/Sub, SSG, Scalability, Server-side Rendering (SSR), Static Site Generators, Web Scalability, Lazy Loading, Caching, CI/CD Pipelines, A/B Testing, Security, Startups, Chrome DevTools, Page Speed Optimization, Pixel Perfect, AI-generated Code, API Integration, Web Scraping, White Box Testing, Bug Fixes, Debugging, Agentic AI, Multi-tenant SaaS, Cross-browser Compatibility, QA Automation, Mobile First, Distributed Systems, Documentation, SaaS, Software System Architecture Development, System Architecture, Payment Processing, Web Development, Fintech, Solution Architecture, AI Tools, Cloud, Vibe Coding, Consumer-facing Products, Data Visualization, Technical Leadership, Error Handling, Event-driven Systems, Containerization, Prompt Engineering, Software Design, High-availability Systems, Row-level Security (RLS), Figma to React, Payment APIs, Website Data Scraping, Deployment, Automations, Scripting, Dashboards, Web Dashboards, API Gateways, RESTFul APIs, Data Processing Automation, Document Parsing, Financial Data, Data Transformation, Third-party APIs, Webhooks, CRM APIs, Back-end, OAuth, Domain-driven Design (DDD), Middleware, Repository Pattern, Legacy Code, Migration, Quality Assurance (QA), Cloud Infrastructure, Early-stage Startups, UI Components, Gatsby, LDAP, Amazon API Gateway, GitHub Actions, WebSockets, General Transit Feed Specification (GTFS), eCommerce, Cryptography, Pedagogy, Technical Writing, PDF, Web Security, Maps, Customer Relationship Management (CRM), Accessibility, Web Accessibility, Artificial Intelligence (AI), General Data Protection Regulation (GDPR), Legal, Amazon RDS, Cursor AI, Supabase, Cloudflare, Large Language Models (LLMs), Video Streaming, Identity Verification, AI Automation, Payments, Algorithms, Internet of Things (IoT), Telemetry, CRM, AI Agents, Real-time Data, Amazon Route 53, Enzyme, Bitcoin, IOTA, Cryptocurrency, HTML Email, Prometheus, SAP Business ByDesign, SAP, Software Engineering, OpenID Connect (OIDC), OpenStreetMap, Routing, App Store Connect, Cryptocurrency Wallets, Rithum, Azure Serverless Functions, Azure Service Bus, EDIFACT, Hash, Routing Controllers, Vite, TanStack Query, Microsoft Identity Platform, Reinforcement Learning from Human Feedback (RLHF), FastAPI, Robotics, Optical Character Recognition (OCR), Video Processing, Pgvector, Vector Databases, BullMQ, AI Integration, Better Auth, Temporal, Wearable Technology, Image Processing, HIPAA, SOC 2, Compliance, Amazon Redshift, Hono, Monorepos, AWS ECS Fargate, RFID, Strapi, Enterprise Resource Planning (ERP), ERP Implementation, Authorization
Collaboration That Works
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
1
Share your needs
Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2
Choose your talent
Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3
Start your risk-free talent trial
Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.
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