10/26/2026 updated

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Senior Frontend Engineer / Tech Lead - React, TypeScript, Node.js

Wrocław, Poland
Worldwide
Wrocław, Poland
Worldwide

Profile attachments

Jaroslaw_Miazga_Senior_Frontend_React_Engineer_CV.pdf

About me

Senior Frontend Engineer & Tech Lead with 19+ years of experience. I currently lead a team of 5 engineers, for whom I architected and built an internal analytics platform from the first commit, now used by users across many teams.

PHPArchitectureCode CoverageNode.jsNext.jsTypeScriptReact.jsGoogle FirebaseBackendWebpackGraphQLReact NativeFront End Software DevelopmentApi DesignNestJS
React & TypeScript Development
Expertise in building modern web applications using React (16 to 19), TypeScript, JavaScript (ES2023), Next.js, Redux Toolkit, RTK Query, Redux-Saga, Recoil, React Query, HTML5, CSS3, Sass, MUI, Styled Components, D3.js and Electron. Over 10 years of specialisation in React and TypeScript across pharma, telecom, SaaS, e-commerce and fintech domains.

Frontend Architecture & Tech Leadership
Proven track record of leading frontend teams, defining architecture and engineering standards, and delivering production web applications. Experience in requirements gathering, prototyping, testing, deployment, mentoring, Agile/Scrum processes and stakeholder communication.

Backend & API Integration
Hands-on experience with Node.js, NestJS, Express, GraphQL, REST, WebSockets, MQTT, PHP and Firebase for building and integrating backend services and APIs.

Testing & Quality Assurance
Proficiency in Jest, React Testing Library, Cypress, Playwright, Unit/Integration/E2E testing, BDD with Cucumber, visual regression testing and code review practices.

Tooling & DevOps
Experience with Vite, Webpack, Docker, Kubernetes, CI/CD pipelines using GitLab CI and GitHub Actions, AWS (Lambda, SQS), Azure, Google Cloud and Git.

Real-Time Communication
Implementation of real-time communication using MQTT over WebSockets between frontend and backend, as well as building real-time messengers and incident-simulation platforms.

Data Visualisation
Building interactive data visualisations with D3.js for web applications, including analytics and data platforms.

Mobile & Cross-Platform Development
Delivery of mobile app web versions using React, Recoil and Firebase, as well as Android app development and cross-platform solutions.

E-Commerce & SaaS Platform Development
Ownership of user-facing sides of large e-commerce platforms and SaaS products, including warehouse management systems, GraphQL API design and full restyling of platforms.

Languages

EnglishFluentItalianGoodPolishNative speakerRussianGoodSpanishGood

Project history

Lead Frontend Engineer / Tech Lead

Boehringer Ingelheim
Leading frontend development of an internal analytics and data platform used across the organisation of a global pharmaceutical company. Gathered requirements, designed and delivered the MVP of a data-access platform, led the frontend team, defined organisation-wide engineering standards, migrated codebase from React 16 to React 19 and from Webpack to Vite, and built CI/CD pipelines and Docker-based environments. Stack: React 19, TypeScript, Redux Toolkit, RTK Query, Redux-Saga, MUI, Vite, Docker, Kubernetes, CI/CD.

Lead Frontend Engineer

Plume Design, Inc.
Owned the frontend architecture of a web application for a US smart-home / Wi-Fi SaaS provider. Defined the frontend architecture, led refactoring of legacy code, introduced TypeScript, unit testing, feature flags and a multi-language (i18n) UI, built interactive data visualisations with D3.js, and mentored other engineers. Stack: React, TypeScript, Recoil, Redux, D3.js, Jest, i18n.

Lead Frontend Engineer

UptimeLabs
Designed and built from scratch the UI of a real-time incident-simulation (outage game) platform for SRE/DevOps training. Designed a scalable frontend architecture, implemented real-time communication with MQTT over WebSockets, ran UX research and live user-testing sessions, and set up unit and E2E test suites. Stack: React, TypeScript, MQTT, WebSockets, Jest, Cypress, headless CMS.

Senior Frontend Engineer

UNUM
Built and maintained the main web product and led the rewrite of internal tools for a US content-creation platform. Delivered the web version of a mobile app for storytellers and content creators using React, Recoil and Firebase, led the from-scratch rewrite of the internal admin application, drove sprint-level delivery planning and won the company hackathon. Stack: React, TypeScript, Recoil, Firebase.

Senior Full-Stack Engineer (JavaScript)

MuscleFood
Owned the user-facing side of a large e-commerce platform and its internal applications. Built a Warehouse Management System (React, Redux, Redux-Saga), designed and implemented a GraphQL API on NestJS with third-party integrations, and coordinated a full restyling of the e-commerce platform. Stack: React, Redux, Redux-Saga, Node.js, NestJS, GraphQL, Sass.

Backend Engineer (Node.js, contract)

Birdie
Built real-time integrations with external APIs on NestJS, TypeScript, AWS Lambda and AWS SQS; covered with unit and integration tests; contributed Architecture Decision Records.

Full-Stack Engineer

Directly
Developed a customer-support platform serving enterprise clients including Microsoft, Samsung, Airbnb, LinkedIn and Husqvarna. Built a real-time messenger, delivered new features and resolved performance and security issues across the platform using ES6, Node.js, React/Redux, Groovy/Grails and Java in a Scrum team.

Senior Frontend Engineer

SMT Software
Designed and built an SPA blog module (AngularJS) and a reusable CMS component library for a London fintech startup; introduced BEM and BDD (CucumberJS); reached 90% unit-test coverage (Jasmine, Chai, Karma) and added visual CSS regression testing.

Full-Stack Engineer

Dictionary.com
Part of a 20-engineer team that rewrote the entire Dictionary.com application; maintained the legacy backend, decommissioned redundant features, built an end-to-end acceptance-testing framework (Behat, Docker) and refactored legacy code to PSR-4 standards.

Frontend Developer

Unity S.A.
Implemented new layouts for a Java (JSP/JSTL) e-commerce platform; migrated CSS to modular Sass; reviewed code and raised team coding standards.

Software Developer

Linkeo
Built web and mobile applications for multiple clients at an interactive agency: a news portal with a panorama editor, a password manager, a car-rental system, an Android app, newspaper-production tools and LED-screen applications.

Freelance Web & Mobile Developer

Freelance
Delivered websites on a self-built CMS, co-developed the NFHotel hotel-management system and published Android apps including Bitwa Gorlicka 1915 on Google Play.

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