Jozsef is available for hire
Hire JozsefJozsef Varga
Verified Expert in Engineering
Front-end Developer
Budapest, Hungary
Toptal member since October 14, 2022
Bio
József is a confident software engineer with 15+ years of experience, specializing in modern front-end architecture. He’s highly proficient in TypeScript, React, and Node.js, and is known for his methodical, problem-solving mindset, often described as having a "detective’s" approach to engineering. József thrives in global, remote teams and brings clarity, precision, and reliability to every project.
Portfolio
FYLD
React, TypeScript, JavaScript, Node.js, Vite, Vitest, Redux, Redux-Saga...
Acrolinx
TypeScript, React, Node.js, CI/CD Pipelines, Webpack, Cypress, Vite, Jest...
Adverity
JavaScript, TypeScript, React, Redux, React Redux, Redux-Saga, Highcharts...
Experience
- Software Architecture - 15 years
- JavaScript - 15 years
- Node.js - 12 years
- Unit Testing - 8 years
- E2E Testing - 8 years
- TypeScript - 7 years
- React - 7 years
- Cypress - 3 years
Preferred Environment
Linux, Windows, Windows Subsystem for Linux (WSL), GitHub, Next.js, Server-side Rendering (SSR)
The most amazing...
...tool I've developed is a browser-based photobook editor built upon the Canvas API, capable of manipulating images in multiple ways.
Work Experience
Senior Front-end Developer
2025 - 2026
FYLD
- Enabled members of the public to submit videos of problems (leaks, damage) to utility companies by revamping a customer-facing platform.
- Delivered React application development with a strong focus on high performance and accessibility throughout the platform.
- Implemented a comprehensive test system using Vitest, enabling thorough unit, integration, and component test coverage across the application with CI/CD support.
- Managed AI-assisted development with tools such as Claude and Copilot.
Technologies: React, TypeScript, JavaScript, Node.js, Vite, Vitest, Redux, Redux-Saga, Material UI, AI-assisted Development, Artificial Intelligence (AI), Claude, Claude Code, API Management, User Experience (UX), User Interface (UI), Debugging, Chrome DevTools, Web Standards, Data-driven Dashboards, AI Tools, Web Application Architecture, AI-generated Code
Senior Front-end Developer
2023 - 2025
Acrolinx
- Collaborated on an 8-person, cross-functional global team, operating within an Agile workflow using Kanban boards in Jira.
- Worked closely with other teams, including site reliability, language engineers, and translators, to successfully deliver key product features.
- Shaped the front-end architecture, guiding critical upgrades and modernizations, such as transitioning from Webpack to Vite and improving overall code maintainability.
- Created a React-based component and utility library on top of Vite architecture with automated CI/CD, which deploys to npm and CDN. The library is used across four applications, directly boosting developer productivity.
- Implemented a reusable client-side LaunchDarkly provider for practical feature flag usage. Optimized flag evaluations, leading to a 70% reduction in unnecessary checks and significant cost savings.
- Developed robust user interfaces in React, focusing on optimizing rendering performance and ensuring accessibility standards. Optimized the user management UI, achieving a 5x performance improvement by preventing unnecessary renders.
- Implemented a comprehensive testing strategy, including end-to-end and component tests with Cypress, unit tests with Jest, and Storybook stories for validation to ensure our test coverage exceeds 90%.
Technologies: TypeScript, React, Node.js, CI/CD Pipelines, Webpack, Cypress, Vite, Jest, E2E Testing, Unit Testing, Web Components, Component Testing, Storybook, APIs, Application State Management, Automated Testing, Agile, Software Architecture, Web Development, Software Engineering, Internationalization, i18n, Page Speed Optimization, CSS3, React Hooks, RESTFul APIs, UI Frameworks, Containerization, React Query, Figma to React, Zustand, Front-end Development, MySQL, Microservices, Docker, WCAG 2, Back-end, Lazy Loading, Front-end Architecture, Web Performance Optimization (WPO), Scalability, Accessibility, Web Accessibility, API Design, Testing, Microfrontends, API Integration, Dashboards, Architecture, Cloud Deployment, Deployment, SaaS, Authentication, Scrum, Startups, Prompt Engineering, Minimum Viable Product (MVP), Playwright, Code Review, Multi-tenant Architecture, Performance Optimization, Troubleshooting, AI-assisted Development, Artificial Intelligence (AI), API Management, User Experience (UX), User Interface (UI), Debugging, Chrome DevTools, Web Standards, Data-driven Dashboards, AI Tools, Web Application Architecture, AI-generated Code, Technical Leadership, Core Web Vitals, A/B Testing
Senior Full-stack Developer
2019 - 2022
Adverity
- Developed modern React functional and reusable components as generic table components.
- Implemented proper and reusable states with built-in Redux and React mechanisms.
- Worked in various agile teams of 5–6 people with front-end and back-end developers, product managers, UX designers, and QA testers.
- Built and configured various types of charts to visualize data.
- Enhanced data calculation algorithms, doubling the speed and reducing the calculation time.
- Implemented a mock service in Node.js, providing fake data for the client application.
- Added a microservice that handled notification requests to be processed and forwarded to Slack and Microsoft Teams.
- Transitioned legacy parts of the applications into modern, reusable components.
- Collaborated closely with UI/UX designers and other departments.
Technologies: JavaScript, TypeScript, React, Redux, React Redux, Redux-Saga, Highcharts, Lodash, Remeda, Design Systems, Node.js, NPM, NestJS, MongoDB, PostgreSQL, Jest, Cypress, Storybook, Lerna, Webpack, ESLint, Monorepos, Unit Testing, Integration Testing, E2E Testing, CSS, Responsive UI, Single-page Applications (SPAs), APIs, Full-stack, REST APIs, Data Visualization, Web Applications, Agile, HTML, Front-end, Sass, HTML5, Data Engineering, Git, Tailwind CSS, REST, Puppeteer, ECMAScript (ES6), GitHub, Application State Management, Material UI, Reusable Libraries, Test-driven Development (TDD), Vite, Jira, Webhooks, JSON, CI/CD Pipelines, Software Architecture, Web Development, Software Engineering, Internationalization, i18n, Page Speed Optimization, CSS3, React Hooks, RESTFul APIs, UI Frameworks, React Query, Figma to React, Front-end Development, Microservices, Back-end, Lazy Loading, Front-end Architecture, Web Performance Optimization (WPO), Scalability, Accessibility, Web Accessibility, API Design, Testing, Microfrontends, API Integration, Dashboards, Architecture, Cloud Deployment, Deployment, SaaS, Authentication, Scrum, Back-end Development, Full-stack Development, Startups, Minimum Viable Product (MVP), Code Review, Multi-tenant Architecture, Performance Optimization, Troubleshooting, API Management, User Experience (UX), User Interface (UI), GraphQL, Debugging, Chrome DevTools, Web Standards, Data-driven Dashboards, Web Application Architecture, React Testing Library, A/B Testing
Senior Front-end Developer
2017 - 2019
SICOM Systems
- Implemented Ext JS components for restaurant management and back office applications.
- Collaborated closely with back-end engineers to deliver a suitable API contract.
- Added multiple unit, end-to-end (E2E), and automated tests for Ext JS applications.
- Managed the upgrade from Ext JS 5 to Ext JS 6, which required refactoring the components.
Technologies: JavaScript, JavaScript Testing, Ext JS, Unit Testing, E2E Testing, Automated Testing, CSS, Responsive UI, Single-page Applications (SPAs), APIs, Full-stack, REST APIs, Web Applications, Agile, HTML, Front-end, Sass, HTML5, Data Engineering, Git, REST, ECMAScript (ES6), Application State Management, Reusable Libraries, Test-driven Development (TDD), JSON, Software Architecture, Web Development, Software Engineering, CSS3, RESTFul APIs, UI Frameworks, Front-end Development, Back-end, Front-end Architecture, Testing, API Integration, Dashboards, Architecture, SaaS, Authentication, Scrum, Minimum Viable Product (MVP), Code Review, Multi-tenant Architecture, Troubleshooting, User Experience (UX), User Interface (UI), Debugging, Chrome DevTools, Web Standards, Web Application Architecture
Senior Front-end Developer
2015 - 2017
Avon Products
- Implemented features in AngularJS for an Avon representative's application.
- Collaborated with back-end engineers on API design.
- Worked in various agile teams of 5–6 people with front-end and back-end developers, product managers, UX designers, and QA testers.
- Enhanced the internal Grunt build tool to speed up multiple processes.
- Mentored junior colleagues and helped them solve the onboarding challenges.
Technologies: JavaScript, AngularJS, Bootstrap, Lodash, Moment.js, Sass, Bower, Grunt, Gulp, Protractor, Karma, CSS, Responsive UI, Single-page Applications (SPAs), APIs, Full-stack, REST APIs, Web Applications, Agile, HTML, Front-end, HTML5, Data Engineering, Git, REST, ECMAScript (ES6), Application State Management, Reusable Libraries, Test-driven Development (TDD), JSON, Software Architecture, Web Development, Software Engineering, CSS3, RESTFul APIs, UI Frameworks, Front-end Development, Lazy Loading, Front-end Architecture, API Design, Testing, API Integration, Dashboards, SaaS, Authentication, Scrum, Back-end Development, Full-stack Development, Code Review, Troubleshooting, User Experience (UX), User Interface (UI), Debugging, Chrome DevTools, Web Standards, Web Application Architecture
Front-end Developer
2014 - 2015
Morgan Stanley
- Added unit, automated, and E2E tests to the application.
- Implemented features in Ext JS, from the Ext JS 4 to Ext JS 6 version.
- Participated in the development of a common client framework.
- Collaborated closely with back-end engineers and other departments.
Technologies: JavaScript, Ext JS, Node.js, Grunt, Unit Testing, E2E Testing, Automated Testing, Sencha Cmd, Sencha UI, Sencha Touch, CSS, Single-page Applications (SPAs), APIs, REST APIs, Web Applications, Agile, HTML, Front-end, Sass, HTML5, Git, REST, Application State Management, Reusable Libraries, JSON, Software Architecture, Web Development, Software Engineering, CSS3, RESTFul APIs, UI Frameworks, Front-end Development, Testing, API Integration, Dashboards, Scrum, Back-end Development, Full-stack Development, Code Review, Troubleshooting, User Interface (UI), Debugging, Web Standards
Front-end Developer
2013 - 2014
EPAM Systems
- Implemented features in Ext JS in a secure environment.
- Fixed various bugs in the front-end part of the system.
- Worked in an agile team of six people with front-end and back-end developers and QA testers.
Technologies: JavaScript, Ext JS, CSS, Single-page Applications (SPAs), APIs, REST APIs, Web Applications, HTML, Front-end, HTML5, Git, REST, Application State Management, Reusable Libraries, JSON, Software Architecture, Web Development, Software Engineering, CSS3, RESTFul APIs, UI Frameworks, Front-end Development, API Integration, Code Review, Troubleshooting, User Interface (UI), Debugging, Web Standards
Front-end Developer
2012 - 2013
MadTatu LLC
- Developed a Canvas-based photobook editor with jQuery and native JavaScript.
- Collaborated closely with the design team to be able to parse photobook templates.
- Worked with different browser APIs and cross-browser functionalities.
Technologies: JavaScript, Canvas, jQuery, jQuery UI, SVG, CSS, Single-page Applications (SPAs), APIs, SQL, Full-stack, REST APIs, Web Applications, HTML, Front-end, Sass, HTML5, Git, LAMP, REST, Application State Management, Reusable Libraries, JSON, Software Architecture, Web Development, Software Engineering, CSS3, RESTFul APIs, UI Frameworks, Front-end Development, MySQL, Back-end, API Design, API Integration, Back-end Development, Full-stack Development, Code Review, Troubleshooting, User Interface (UI), PHP, Debugging, Web Standards
Experience
Adverity
https://www.adverity.com/Adverity is an integrated data platform enabling marketing, sales, and eCommerce teams to make better decisions and improve performance. I took part in the development of their two major products as a senior front-end developer.
Dice Wars
This project was my university thesis project. It is a multiplayer browser-based game built entirely on the Canvas API, where players are scattered around a hexagon-tiled map to occupy the most tiles by rolling dice in a turn-based style. The communication between players was achieved using the WebSocket API connected to a Node.js-based server.
Web-based Photo Book Editor
A Canvas API-based web application for creating photobooks easily with multiple templates, image editing capabilities, and much more. I led the project alone as a front-end developer and used mainly plain JavaScript.
Education
2004 - 2009
Bachelor's Degree in Software Engineer and Mathematics
Eötvös Loránd University - Budapest, Hungary
1999 - 2004
Technical Diploma in Computer Engineering
János Bolyai Technical School - Budapest, Hungary
Skills
Libraries/APIs
React, Node.js, REST APIs, React Redux, Highcharts, React Query, React Testing Library, Redux-Saga, Lodash, Moment.js, jQuery, jQuery UI, Socket.IO, Puppeteer, Playwright
Tools
NPM, Git, GitHub, Lerna, Webpack, JavaScript Testing, Bower, Grunt, Gulp, Karma, Sencha Cmd, Sencha UI, Canvas, Jira, Vitest, Claude, Claude Code
Languages
JavaScript, TypeScript, HTML5, CSS3, CSS, HTML, ECMAScript (ES6), SQL, Sass, GraphQL, PHP
Paradigms
Unit Testing, E2E Testing, Testing, Web Application Architecture, Agile, Scrum, REST, Microservices, Web Performance Optimization (WPO), Microfrontends, Automated Testing, Test-driven Development (TDD)
Storage
JSON, MySQL, Cloud Deployment, Relational Databases, MongoDB, PostgreSQL
Frameworks
Redux, NestJS, Jest, Cypress, Express.js, Ext JS, AngularJS, Bootstrap, Protractor, Sencha Touch, Tailwind CSS, Material UI, Next.js
Platforms
Linux, Windows, LAMP, Docker
Other
Software Architecture, Software Engineering, Single-page Applications (SPAs), APIs, Full-stack, Web Applications, Front-end, Application State Management, React Hooks, RESTFul APIs, UI Frameworks, Figma to React, Front-end Development, Front-end Architecture, API Integration, Dashboards, Architecture, SaaS, Minimum Viable Product (MVP), Code Review, Multi-tenant Architecture, Performance Optimization, Troubleshooting, User Experience (UX), User Interface (UI), Debugging, Chrome DevTools, Web Standards, Data-driven Dashboards, AI Tools, Data Visualization, Responsive UI, Data Engineering, Reusable Libraries, Vite, Internationalization, i18n, Page Speed Optimization, Zustand, Back-end, Lazy Loading, Scalability, Deployment, Back-end Development, Full-stack Development, Startups, AI-assisted Development, Artificial Intelligence (AI), API Management, AI-generated Code, Core Web Vitals, Web Development, Windows Subsystem for Linux (WSL), Algorithms, Mathematics, Design Systems, Storybook, ESLint, Monorepos, Integration Testing, SVG, WebSockets, Remeda, Webhooks, CI/CD Pipelines, Web Components, Component Testing, Containerization, WCAG 2, Accessibility, Web Accessibility, API Design, Authentication, Prompt Engineering, Server-side Rendering (SSR), Technical Leadership, A/B Testing
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