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Lukasz Luczak
Verified Expert in Engineering
React Developer
Warsaw, Poland
Toptal member since September 10, 2021
Bio
Lukasz is a seasoned software developer specializing in TypeScript/JavaScript and Node.js, and React, with strong analytical skills and over a decade of experience transforming ideas into working software solutions. With a master's degree in computer science, Lukasz has extensive knowledge of programming the back ends of web and mobile apps, relational database modeling, REST API design, and agile approaches to delivering value.
Portfolio
Zoetis - Digital Manufacturing
React, User Experience (UX), JavaScript, CSS, User Interface (UI), HTML, SAP...
J2 Health
JavaScript, Python 3, Big Data, Google Cloud, Git, GitHub, GitHub Actions...
Simple Network Analytics LLC
React, Node.js, JavaScript, SQL, Google Cloud, Front-end Development...
Experience
- JavaScript - 10 years
- React - 9 years
- Node.js - 7 years
- Full-stack - 6 years
- SQL - 5 years
- TypeScript - 3 years
- AI Agents - 2 years
- Next.js - 2 years
Preferred Environment
MacOS
The most amazing...
...project I've developed is a progressive web app for kids and their parents that got 4.67 out of five stars from the 1st reviewers.
Work Experience
Front-end Developer
2025 - 2025
Zoetis - Digital Manufacturing
- Implemented MVP app UI using React and TypeScript in a record time of six weeks, starting from scratch.
- Released a working MVP with fully set up CI/CD automation running automated tests.
- Managed the work of one junior developer with mentoring, code reviews, and pair coding.
Technologies: React, User Experience (UX), JavaScript, CSS, User Interface (UI), HTML, SAP, TypeScript, REST APIs, Vite, Vitest, React Query, Tailwind CSS, Shadcn, Debugging, Tailwind UI, Claude Code, Code Review, Automated Testing, Artificial Intelligence (AI)
Senior Full-stack Engineer
2022 - 2024
J2 Health
- Developed a new version of the Node.js back-end API that served the front-end app.
- Built a new version of the front-end application based on React, Redux, and React Router.
- Helped transition the back-end API to Python from Node.js.
- Built an internal tool for data administrators (admin panel).
Technologies: JavaScript, Python 3, Big Data, Google Cloud, Git, GitHub, GitHub Actions, TypeScript, Redux, React Router, React, Mapbox GL, Django, Remix, Front-end, API Integration, PostgreSQL, REST, Express.js, Front-end Development, Full-stack Development, Next.js, Python, Full-stack, Back-end Development, Back-end, Web App Development, Web Development, User Experience (UX), API Design, Figma, Unit Testing, Web Applications, CSS3, React Hooks, RESTFul APIs, Google Cloud Platform (GCP), API Development, Debugging, Code Review, Automated Testing, Artificial Intelligence (AI), Startups, AI Agents
Full-stack Developer
2021 - 2022
Simple Network Analytics LLC
- Modernized front-end app tech stack that allowed faster deployments and feature releases.
- Tracked and fixed bugs using Jira as a ticketing system.
- Prepared the data for application demos for potential clients.
Technologies: React, Node.js, JavaScript, SQL, Google Cloud, Front-end Development, Full-stack Development, Full-stack, Back-end Development, Back-end, Web App Development, Web Development, Unit Testing, Web Applications, CSS3, React Hooks, Google Cloud Platform (GCP), API Development, Legacy Code, Debugging, Automated Testing
Senior Front-end Developer
2021 - 2022
Waitrose
- Implemented new features for promotion campaigns.
- Tracked and fixed bugs related to the UI and back end.
- Built reusable UI components used across the site.
Technologies: JavaScript, TypeScript, Node.js, CSS, HTML5, Front-end, API Integration, Front-end Development, Web App Development, Web Development, User Experience (UX), Figma, Unit Testing, Web Applications, CSS3, React Hooks, CI/CD Pipelines, Debugging, Code Review, Automated Testing
Senior JavaScript and React Developer | Tech Lead
2015 - 2021
Weblify
- Implemented a dozen applications' front ends on React with Material UI, Redux, React Admin, React Charts, and more.
- Implemented application back ends with Node.js and PostGREST with requirements analysis and relational database modeling.
- Built mobile applications for iOS (Swift) and Android (Kotlin).
- Developed an in-house static site generator to quickly create websites with high scores in page speed tests.
- Carried out pair programming, code reviews, and junior developers' mentoring.
Technologies: JavaScript, React, Node.js, PostgreSQL, PostgREST, Docker, React Redux, Redux, Express.js, Web App Design, Web UX Design, Web App UX, Web App Testing, CSS, HTML, Scrum, Agile, Functional Programming, Domain Modeling, Jest, React Testing Library, Jamstack, APIs, Software Architecture, REST APIs, Git, Amazon S3 (AWS S3), AWS Lambda, Amazon Simple Email Service (SES), Slack, Redmine, Responsive Web Design (RWD), Responsive Web Apps, HTML5, JSON, Front-end, API Integration, Front-end Development, Full-stack, Technical Leadership, Web App Development, Minimum Viable Product (MVP), Web Development, Unit Testing, Web Applications, CSS3, RESTFul APIs, API Development, Debugging, Code Review
Founder | Web Development Manager
2010 - 2015
Weblify
- Owned the architecture of every application built for clients.
- Oversaw the introduction of Node.js as a platform for back ends and helped implement it for the first customers.
- Introduced React as a tool for SPAs and implemented web UIs with it.
- Managed team of Ruby and JavaScript developers and provided technical expertise.
Technologies: IT Services, Agile, Scrum, Web App Design, Web UX Design, JavaScript, Software Architecture, Git, Jira, Redmine, Front-end, API Integration, Full-stack, Technical Leadership, Web App Development, Minimum Viable Product (MVP), Web Development, Web Applications
Founder | Web Developer
2008 - 2010
One99
- Designed and led the implementation of a Polish FourSquare-inspired geolocation app.
- Designed and developed the app that allowed to group up customer purchases and obtain bulk-purchase discounts during the reverse auction for suppliers.
- Contributed to creating and executing algorithms for determining the winner of multi-params reverse auctions.
Technologies: Scrum, Agile, JavaScript, REST APIs, HTML5, HTML, JSON, Ruby on Rails (RoR), API Integration, Full-stack Development, Back-end Development, Back-end, Web App Development, Minimum Viable Product (MVP), Web Development, Web Applications
Senior Business Intelligence Consultant | Team Leader
1999 - 2007
SAP
- Implemented over 20 SAP BI solutions for top Polish enterprises in the fields of finance, controlling, materials management, and sales.
- Created and led the business intelligence consultants' team in SAP Poland, making it one of the most profitable teams in the consulting department.
- Contributed to each project implementation stage: business blueprint, system configuration, ABAP programming, tests cases preparation, and end-user training.
- Won the consultant of the year title for extraordinary performance and customer satisfaction.
- Provided dozens of business intelligence training courses in the SAP Poland training center.
Technologies: SAP Business Intelligence (BI), Team Management, IT Consulting, Web App Development, SAP
Experience
Health Network Analytics
https://j2health.com/A JavaScript prototype application designed to assist health insurers in preparing their provider networks for submission, calculating key adequacy metrics, and visualizing critical data insights through advanced analytics tools.
App for Building Children's Good Habits
A React-based progressive web application for families to build children's good habits.
I was the front-end developer who designed and implemented the UI and I also owned database models, REST APIs design, and integration with the back end. Besides the common React applications elements, I implemented PWA features like a web push notification and adjusted the mobile look and feel to resemble a native mobile app.
I was the front-end developer who designed and implemented the UI and I also owned database models, REST APIs design, and integration with the back end. Besides the common React applications elements, I implemented PWA features like a web push notification and adjusted the mobile look and feel to resemble a native mobile app.
App for Monitoring IoT Sensors Data
A React app for visualizing and monitoring data gathered from IoT sensors.
I was the front-end developer responsible for the charting module and the back-end developer (PostGREST and Node.js) that developed APIs for storing and transforming raw data, providing web and mobile apps to clients below the performance estimation of 250ms.
I was the front-end developer responsible for the charting module and the back-end developer (PostGREST and Node.js) that developed APIs for storing and transforming raw data, providing web and mobile apps to clients below the performance estimation of 250ms.
Custom Static Site Generator
A Node.js-based static site generator using JSX (React) for templating, Markdown for content, and Vanilla JavaScript for runtime scripting. This app generates SEO-optimized sites, some of which have already achieved high and often perfect scores in page performance tests.
I designed and implemented the app in Node.js.
I designed and implemented the app in Node.js.
Quiz App
A React-based mobile-optimized quiz app developed for a specific event—market introduction of a smartphone manufacturer's new model, addressed at telemarketer partners.
I was the front-end developer who also designed database models used for storing data.
I was the front-end developer who also designed database models used for storing data.
POP Comics Reader
http://www.popcomics.comA React-based mobile and desktop ePub and comics reader that is part of POP Comics.
I was the front-end developer who also helped back-end engineers define the format of the comics' content and the transformation from an ePub format to a POP Comics content structure.
I was the front-end developer who also helped back-end engineers define the format of the comics' content and the transformation from an ePub format to a POP Comics content structure.
Company Websites
Several company websites built with a custom static site generator, JavaScript, and React.
I was the front-end developer who implemented the graphical designers’ visions and took care of the SEO correctness and performance optimization.
Some of my recent works include:
• https://www.apexit.com
• https://www.se16n.com/en/
I was the front-end developer who implemented the graphical designers’ visions and took care of the SEO correctness and performance optimization.
Some of my recent works include:
• https://www.apexit.com
• https://www.se16n.com/en/
AI Chat Bot for Medical Appointments
A Next.js TypeScript AI chatbot app allows users to make medical appointments in New York City by chatting with an AI agent. Based on user input, the agent suggests clinics/doctors and makes a phone call to make a booking.
Education
1994 - 1999
Master's Degree in Computer Science
Poznan University of Technology - Poznan, Poland
Skills
Libraries/APIs
Node.js, React, React Redux, REST APIs, React Router, API Development, PostgREST, React Testing Library, Drizzle, Mapbox GL, React Query
Tools
Redux Thunk, JSX, Slack, Knex.js, Rollup, Git, Create React App, Redmine, GitHub, Shadcn, Claude Code, Jira, Amazon Simple Email Service (SES), Figma, Vitest
Languages
SQL, JavaScript, HTML, CSS, HTML5, TypeScript, CSS3, Python, Python 3
Frameworks
Redux, Next.js, Express.js, Jest, Remix, Tailwind CSS, Material UI, Django, Ruby on Rails (RoR)
Paradigms
REST, Web App Design, Responsive Web Design (RWD), Scrum, Agile, Functional Programming, Web UX Design, Jamstack, Unit Testing, Automated Testing
Platforms
MacOS, Amazon Web Services (AWS), Docker, AWS Lambda, Google Cloud Platform (GCP)
Storage
JSON, SQLite, PostgreSQL, Databases, Amazon S3 (AWS S3), Google Cloud, MySQL
Other
IT Services, Responsive Web Apps, Front-end, API Integration, Front-end Development, Full-stack Development, Full-stack, Web App Development, Web Applications, React Hooks, RESTFul APIs, Code Review, Responsive UI, Startups, Progressive Web Applications (PWAs), Web Notifications, Domain Modeling, SAP Business Intelligence (BI), Team Management, IT Consulting, Web App UX, Web App Testing, APIs, Software Architecture, PWA, Agentic AI, Technical Leadership, Back-end Development, Back-end, Minimum Viable Product (MVP), Web Development, AI Agents, User Experience (UX), API Design, AI Tools, User Interface (UI), SAP, CI/CD Pipelines, Supabase, Legacy Code, Debugging, Tailwind UI, Artificial Intelligence (AI), ECS, AI Development, Big Data, GitHub Actions, AI Chatbots, OpenAI, Vite
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