Marek Lisik, Developer in Luxembourg City, Luxembourg
Marek is available for hire
Hire Marek

Marek Lisik

Verified Expert  in Engineering

Native Mobile Developer

Luxembourg City, Luxembourg
Toptal Member Since
July 12, 2021

Marek is a React Native developer with a background in native mobile development and project management. After years of programming roles and leading projects, he took a deep dive into React Native and hasn't looked back, helping clients kick off and maintain their mobile products. He has taken on large legacy codebase rewrites, built reusable libraries for core features, and created an end-to-end testing suite using React and Detox and a catalog app complete with checkout and 3D product models.


Forbes Media -
JavaScript, React Native, TypeScript, Redux, Redux Toolkit, Detox, E2E Testing...
JavaScript, TypeScript, React Native, Java, Android, Swift, Objective-C...
JavaScript, TypeScript, React Native




Preferred Environment

MacOS, Visual Studio Code (VS Code), TypeScript, React Native, Xcode, Git, Swift

The most amazing...

...project I've delivered was a set of proof-of-concept apps and tools for a new electric moped prototype at Ujet, a multidisciplinary, cross-platform challenge.

Work Experience

Senior React Native Developer and Front-end Team Lead

2021 - 2022
Forbes Media -
  • Led a front-end team of 3-5 developers, often working as a liaison between Product and Engineering and coordinating requirements with other technical teams.
  • Prepared a strategy to improve a legacy, low-quality codebase by following modern best practices.
  • Improved our unit and integration test coverage, elevating the team's ability to deliver tested and testable code.
  • Rolled out one major and one minor global redesign of the mobile app, delivering a universal design system package in the process.
  • Took ownership of an API gateway project in NestJS to deliver a single point of access for data required by the mobile app.
Technologies: JavaScript, React Native, TypeScript, Redux, Redux Toolkit, Detox, E2E Testing, Unit Testing, Integration Testing, NestJS, Firebase

Senior Mobile Applications Developer

2019 - 2021
  • Maintained a legacy app for the company's flagship electric two-wheeler with an ongoing effort towards better performance and modernizing the code base to use TypeScript and best practices.
  • Built a SwiftUI virtual BLE peripheral (MacOS and iOS) for testing and debugging our Bluetooth services and update protocols.
  • Prepared reusable in-house libraries for over-the-air and device firmware updates using BLE.
  • Managed and automated continuous integration and continuous deployment using Bitbucket and Visual Studio App Center.
  • Built an end-to-end testing suite using Detox, complete with a mock server to control the behavior of mocked external services during test runtime.
Technologies: JavaScript, TypeScript, React Native, Java, Android, Swift, Objective-C, Bluetooth LE, iOS, SwiftUI, MacOS

Senior React Native Developer

2018 - 2019
  • Built a large product for the hospitality industry and a white label multifunctional chat app for a car dealership that also offers maintenance services.
  • Coordinated the creation of a best-practices repository to consolidate processes and infrastructure across development teams.
  • Mentored new hires, prepared technology talks, and researched Flutter development.
  • Participated in specification reviews, estimates, expert calls, and scoping sessions with new and potential clients.
Technologies: JavaScript, TypeScript, React Native

React Native Developer

2017 - 2018
  • Built a small furniture catalog mobile app complete with checkout process and 3D product models.
  • Rewrote a legacy app for a short-time e-moped and bike rental platform, working against a tight deadline and fixed requirements, then continued to the maintenance and expanding the feature set after launch.
  • Contributed to the planning and development of new features and prepared design comps and user flows for credit card management and document uploads.
  • Managed and automated the process of testing and release build distribution.
Technologies: JavaScript, React Native, Redux, Maps

IT Project Manager

2012 - 2017
  • Consulted with clients and the development team to build up project specifications.
  • Prepared detailed user stories and planned out our development efforts in Jira.
  • Coordinated our project work, evaluated, and adapted on an ongoing basis.
  • Organized and led daily stand-up meetings, planning sessions, retrospectives, and product demos.
  • Managed resources provided for development by clients and wrote scripts to automate conversions and organization where applicable.
  • Learned the basics of iOS development (Objective-C, then Swift), and became an ad hoc contributor to our codebases.
Technologies: Scrum, Agile, Continuous Deployment, Continuous Integration (CI), IT Project Management, iOS, Objective-C, Swift, UX Direction AI-Powered Investing
A React Native app for managing financial investments. I was onboarded as a senior React Native developer, took ownership of the front-end source, and led the team to maintain a large legacy codebase and build new features. I'm proud of improving our TypeScript typing coverage and accuracy and bringing in utilities to help developer experience around it, elevating our unit and integration test coverage, building out a comprehensive design system based on our designers' documentation, multiple bug bashes that helped identify core issues across the front and back end as well as gaps in our understanding of the product.

Ujet Connect
A React Native companion app for a connected, electric two-wheeler. The app allows tracking the vehicle position, sharing access with friends, unlocking and monitoring errors, access to support, and locating maintenance stations. My focus was on maintenance, clearing a large backlog of bugs, inconsistencies, and improvements, and on an ongoing rewrite to use modern React practices. I made the codebase more modular and testable, introduced TypeScript and unit and integration tests, and developed brand-new features. Moped Sharing App
A React Native app for short-time moped and bicycle rentals. I came in to rewrite the previous version of the app from scratch in time for the new season. As the only mobile developer, I collaborated closely with the client and the back-end team on building up requirements and guiding the project forward. We used maps to help users find their vehicles, integrated payment processing (Straal), document uploads for KYC, and robust rental state management.


TypeScript, JavaScript, Swift, Java, Objective-C


React Native, Redux, SwiftUI, NestJS, UIKit, Tailwind CSS


English, Mobile App Development, IT Project Management, Maps, Research & Critical Thinking, UX Direction, Integration Testing, Redux Toolkit, Detox, Libraries


React, Redux-Saga, D3.js


Xcode, Git, Plaid


Scrum, Agile, Continuous Deployment, Continuous Integration (CI), Test-driven Development (TDD), REST, E2E Testing, Unit Testing, Testing


Visual Studio Code (VS Code), Bluetooth LE, iOS, MacOS, Android, Firebase

2006 - 2012

Master's Degree in English

University of Wrocław - Wrocław, Poland

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.


Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.

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.

Top talent is in high demand.

Start hiring