Igor is available for hire
Hire IgorIgor Marinkovic
Verified Expert in Engineering
Front-end React Developer
Niš, Serbia
Toptal member since May 12, 2022
Bio
Igor, a dedicated front-end React developer, is renowned for consistently delivering clean, high-quality JavaScript code throughout his extensive career. Proficient in React, his primary focus is optimizing performance and ensuring quick turnarounds. His commitment to excellence is reflected in his ability to craft seamless user experiences. Igor excels in effective communication and thrives in collaborative teamwork environments.
Portfolio
Clarium Education, Inc.
React, Styled-components, User Interface (UI), User Experience (UX), Shadcn...
disco
TypeScript, React, React Query, Zustand, Tailwind UI, Tailwind CSS, Shadcn...
Variant Perception
React, Next.js, TypeScript, Firebase, Plotly.js, Plotly, Recoil, React Query...
Experience
- React - 8 years
- JavaScript - 8 years
- Redux - 4 years
- TypeScript - 4 years
- Jest - 4 years
- Next.js - 4 years
- Zustand - 1 year
- Tailwind CSS - 1 year
Preferred Environment
MacOS, Slack
The most amazing...
...project I've worked on is a platform called Eequ. It's a peer-to-peer platform for real-life learning that provides a viable alternative to school.
Work Experience
Senior Front-end/React/UI/UX Developer
2025 - 2026
Clarium Education, Inc.
- Led front-end ownership for a large-scale AI-powered edtech platform, delivering and stabilizing key user-facing experiences across the learner-facing product while supporting rapid product iteration in a startup environment.
- Architected the initial front-end structure for a complex React and TypeScript application, establishing scalable patterns for state management, feature organization, and maintainable component architecture.
- Built and optimized high-impact learner workflows across core user journeys, improving usability, engagement, and product performance.
- Implemented performant server-state management using TanStack Query, improving data-fetching reliability, cache efficiency, and responsiveness across complex product workflows.
- Leveraged AI-assisted development tools to accelerate codebase navigation, implementation, refactoring, debugging, and code reviews while maintaining high engineering standards and final ownership of delivery quality.
- Partnered directly with the founder and team members in a fast-moving startup environment to turn evolving requirements into stable, user-friendly front-end implementations.
- Improved application performance by reducing unnecessary renders, simplifying component flows, and refining data transformation patterns for smoother end-user experiences.
- Strengthened front-end engineering quality by introducing clearer conventions, reusable patterns, and actionable technical guidance during a high-velocity development phase.
Technologies: React, Styled-components, User Interface (UI), User Experience (UX), Shadcn, Tailwind CSS, WebRTC, WebSockets, Zustand, Cursor AI, React Query, LiveKit, TanStack Table, UI Motion, React Motion, Firebase, D3.js, OpenAPI, Playwright, React Testing Library
React and TypeScript Developer
2024 - 2025
disco
- Contributed to preparing Disco’s web platform for public launch by implementing and refining key features.
- Communicated closely with the founder to align on priorities and contribute technical suggestions.
- Delivered critical UI components including authentication, notifications, and robust error handling.
- Integrated React Query for efficient data fetching and API state management.
- Worked independently on time-sensitive features, ensuring quality and consistency.
Technologies: TypeScript, React, React Query, Zustand, Tailwind UI, Tailwind CSS, Shadcn, Caching, Startups
React Developer
2024 - 2024
Variant Perception
- Played a pivotal role in developing and enhancing Variant Perception’s investor portal, focusing on interactive features to deliver tailored financial data, insights, and advanced analytics.
- Developed and customized interactive charts to display complex financial and economic data, ensuring clarity and actionable insights.
- Improved the user interface by adding new features and optimizing existing components, enhancing usability and overall user satisfaction.
- Built personalized dashboards with tailored content feeds, providing users with relevant financial updates and insights.
- Collaborated with the team to prioritize tasks and consistently deliver high-quality results on time.
Technologies: React, Next.js, TypeScript, Firebase, Plotly.js, Plotly, Recoil, React Query, Tailwind CSS, React DnD, Dnd-kit, Firebase Cloud Functions, Cloud Firestore, JavaScript, HTML5, CSS3, Context API, DOM, Typesense, WebSockets, Data Visualization, Caching, Web Scalability, Scalability, Lazy Loading
React Developer
2024 - 2024
apomap
- Engaged by a pharmaceutical startup to play a key role in enhancing their React-based dashboards, ensuring the delivery of critical features within strict deadlines.
- Developed a crucial new feature for barcode scanning, significantly improving the platform’s operational efficiency and user experience.
- Implemented and optimized new functionalities while ensuring high performance across the application.
- Improved existing features and resolved bugs to enhance overall system stability and user satisfaction.
- Emphasized performance optimization throughout development to maintain a smooth and efficient user interface.
- Worked in close collaboration with the team, maintaining open communication to align priorities and ensure timely delivery of tasks.
- Utilized React, TypeScript, Tailwind CSS, React Query, Zustand, Radix UI, Recharts, Zod, and react-easy-crop to deliver high-quality and maintainable code.
Technologies: React, TypeScript, JavaScript, React Query, Tailwind CSS, Tailwind UI, Radix UI, Zustand, Recharts, Zod, react-easy-crop, Lodash, HTML, CSS, Axios, Day.js, i18next, WebSockets, Lazy Loading, Caching, Startups, Front-end Architecture, Scalability
Front-end Developer
2023 - 2023
Reward Gateway, Limited
- Restyled and modernized the existing user interface, utilizing HTML, CSS, and JavaScript, while maintaining backward compatibility with the old codebase, all within a specified and tight timeframe.
- Demonstrated a commitment to iterative improvement, allowing for ongoing refinements based on user feedback and testing results.
- Leveraged React to develop a feature-rich menu editor application involving the implementation of complex algorithms and innovative solutions to address dynamic menu customization.
- Collaborated effectively with an engineering and management team to ensure the app's success.
- Engineered a real-time preview feature that allowed users to visualize their navigation menu's appearance after making changes, contributing to a more intuitive user experience.
- Demonstrated technical prowess by incorporating advanced functionalities such as adding, removing, nesting and unnesting, and reordering menu items and sub-items with precision.
- Created a sophisticated system for adjusting item properties and user interactions to offer users unparalleled customization options.
- Prioritized accessibility standards by adhering to WCAG 2.0 and ARIA attributes, making the admin portal more inclusive.
- Maintained a positive and self-motivated attitude, contributing to a productive team environment. Recognized opportunities for improvement in both project work and delivery processes, actively contributing to the team's success and growth.
- Identified and addressed UX issues during development, proposing alternative solutions for enhanced user satisfaction.
Technologies: Front-end, React, CSS, TypeScript, JavaScript, CSS3, JavaScript Libraries, HTML5, HTML, Sass, WCAG 2, Apollo Server, Apollo, Search Engine Optimization (SEO), Web Content Accessibility Guidelines (WCAG), Web Accessibility
Senior React Developer
2021 - 2023
Synergie Tech Solutions
- Spearheaded the creation of robust proof of concept (POC) solutions, providing critical insights for business-level decision-making.
- Elevated code quality and performance through strategic refactoring, introducing flexible and reusable solutions that contributed to overall system efficiency.
- Engaged in agile sprints, evaluations, and the timely delivery of production-ready solutions, ensuring alignment with project goals.
- Architected the project from its inception, establishing a solid foundation for scalability, maintainability, and future enhancements.
- Identified and resolved software bugs using Jira, collaborating seamlessly with cross-functional team members across various departments.
- Revitalized and enhanced legacy code, adhering to industry standards through meticulous refactoring and feature rewriting, ensuring the long-term sustainability of the codebase.
Technologies: React, Next.js, Material UI, JavaScript, Context API, Segment.io, GraphQL, TypeScript, React Hooks, Unit Testing, Front-end, GitHub, ECMAScript (ES6), API Integration, User Experience (UX), User Interface (UI), CSS, HTML, Sass, Application State Management, APIs, REST APIs, Reusable Libraries, Storybook, HTML5, JSX, DOM, Cypress, Jest, Enzyme, React Router, Functional Programming, PSD to HTML, Code Architecture, Confluence, Figma, Responsive UI, Jira, CSS3, Search Engine Optimization (SEO), Web Performance Optimization (WPO), Web Scalability, Scalability, Core Web Vitals, Static Site Generators, Front-end Architecture, Server-side Rendering (SSR), SSG, Accessibility, Chrome DevTools, Lighthouse
Freelance React Developer
2021 - 2022
Connect Vision
- Delivered project requirements within high-pressure production environments, showcasing adaptability and resilience in meeting stringent timelines.
- Facilitated effective collaboration with diverse teams, swiftly dissecting complex problems, exploring viable solutions, and orchestrating the development of anticipated outcomes.
- Demonstrated expertise by architecting multiple applications within the latest React ecosystem, incorporating cutting-edge technologies to ensure modern, scalable, and feature-rich solutions.
- Committed to code excellence, consistently producing and maintaining clean, efficient, and meticulously documented code to enhance readability, maintainability, and team collaboration.
Technologies: React, React Query, Context API, JavaScript, Pixel Perfect, React Hooks, Ant Design, Styled-components, BrowserStack, TypeScript, Cypress, Unit Testing, Front-end, GitHub, ECMAScript (ES6), API Integration, User Experience (UX), User Interface (UI), CSS, HTML, Application State Management, APIs, REST APIs, Reusable Libraries, Storybook, HTML5, JSX, DOM, React Router, Jest, Enzyme, Functional Programming, Figma, PSD to HTML, Confluence, CSS3
Front-end React Developer
2020 - 2021
EEQU
- Contributed significantly to developing the educational platform's second iteration, leveraging SSR Next.js architecture for improved interactivity and performance.
- Played a vital role in team collaboration by actively conducting code reviews, meticulously planning sprints, estimating features, and setting high code and work standards.
- Took charge of talent acquisition initiatives by designing and evaluating challenging coding challenges and conducting interviews to identify and onboard exceptional candidates.
- Implemented a robust authentication infrastructure using Firebase, reinforcing the platform's security and elevating user authentication capabilities.
Technologies: React, Redux, React Query, Next.js, Material UI, TypeScript, Firebase, JavaScript, BrowserStack, Pixel Perfect, DOM, Formik, Yup, React Hooks, Context API, Unit Testing, Front-end, GitHub, Agile Software Development, Functional Programming, HTML, HTML5, Auth0, CSS, Jest, Enzyme, React Router, Reusable Libraries, Storybook, User Interface (UI), User Experience (UX), ECMAScript (ES6), Agile, Application State Management, Figma, Startups, Front-end Architecture
Lead Front-end React Developer
2019 - 2020
PatronGG GmbH
- Fostered collaboration between developers and designers to construct a progressive web app (PWA) esports platform, facilitating connections between esports organizations and fans through social channels, news updates, and engaging video content.
- Orchestrated the set up of the React-based front-end stack and spearheaded front-end development efforts, ensuring a seamless and visually appealing user experience.
- Provided mentorship and guidance to junior developers, emphasizing the adoption of the latest React development techniques, mainly focusing on the advancements introduced in version 16, including the effective use of Context API and Hooks.
- Engineered features and functionalities with a dedicated focus on speed and performance, optimizing the platform for efficient and satisfying user interaction.
Technologies: React, Material UI, Jest, Enzyme, Context API, Auth0, JavaScript, Yup, React Router, JSDoc, Normalizr, Formik, Front-end, GitHub, Agile Software Development, Progressive Web Applications (PWAs), PWA
Front-end Developer
2018 - 2019
Sabal Tech
- Collaborated with the back-end, testing, and management teams in Scrum methodology to develop a data visualization application that shows the status of daily data management processes.
- Ensured the tests covered the application within 95% efficiency for unit and functional tests with Jest and Enzyme.
- Built the client dashboard with real-time data using Apollo GraphQL.
- Participated in the development of the company's products UI library with Storybook.
Technologies: React, Redux, Material UI, Jest, Enzyme, Recompose, Reselect, Storybook, JavaScript, DOM, CSS, Immutable.js, GraphQL, Front-end, GitHub, Agile Software Development, Figma
Freelance React Developer
2018 - 2018
NEVRON
- Built the TV channels schedule guide software, including Description Panel, Live TV, Timeline, Programming panel (channels), and Show box.
- Developed a complex algorithm for solving live schedule timelines.
- Helped to make crucial decisions regarding requirements and design.
Technologies: React, JavaScript, HTML, CSS
React and React Native Developer
2017 - 2018
Lasting Dynamics
- Developed numerous features on the Anime Web App with React/Redux, including reviews, forums, filters, etc.
- Built the fitness mobile React Native App. The user could search nearby local gyms, pick a day's workout, choose a muscle group, scroll through supplements, and choose a monthly plan. Implemented the integration of Google Places API and FB login.
- Participated from scratch in building a digital card game mobile React Native App. Introduced crucial features for the game's set up, mentored new developers through code control, commented on the progress, corrected bugs, and gave guidelines.
Technologies: React, Redux, React Native, JavaScript, Recompose, Reselect, Immutable.js, Storybook, DOM, CSS, Pixel Perfect, Sass, Bootstrap, HTML
Front-end Developer (Contract)
2017 - 2018
Data Sidekick
- Maintained existing data application that integrates with Salesforce.
- Implemented Google Analytics and optimized processes.
- Solved UI bugs, refactored code, and introduced clean best practices.
Technologies: React, Redux, RxJS, JavaScript, HTML, CSS, Immutable.js
Experience
Reward Gateway | Menu Editor
I take immense pride in the development of a menu editor application using React. This project allowed me to exercise my technical skills and creativity to their fullest extent. From the ground up, I designed and built an application that empowers users to have full control over their platform's navigation menu.
One of the most challenging aspects of this project was implementing complex algorithms to handle menu customization efficiently. Users can seamlessly add, remove, nest, unnest, and reorder menu items and sub-items. They have the flexibility to make granular adjustments, such as modifying item details and user interactions. The real-time preview feature was a significant accomplishment, as it provides users with an instant visual representation of their navigation menu, making the customization process intuitive and user-friendly.
Collaboration was a key element of this project's success, and I am extremely proud of the team I had the pleasure of working with. Together with a dedicated engineering and management team, we ensured that the application not only met user needs but also exceeded design expectations.
One of the most challenging aspects of this project was implementing complex algorithms to handle menu customization efficiently. Users can seamlessly add, remove, nest, unnest, and reorder menu items and sub-items. They have the flexibility to make granular adjustments, such as modifying item details and user interactions. The real-time preview feature was a significant accomplishment, as it provides users with an instant visual representation of their navigation menu, making the customization process intuitive and user-friendly.
Collaboration was a key element of this project's success, and I am extremely proud of the team I had the pleasure of working with. Together with a dedicated engineering and management team, we ensured that the application not only met user needs but also exceeded design expectations.
Eequ
A React-based SSR educational booking platform and marketplace for each person to design their education. The community accepted the platform very well and became a champion for in-person learning and authentic mentoring relationships, filling a vital gap in the current over-digitized sector.
AC Integrated Data Management and Analytics
Previously part of Asset Control, nowadays Alveo, the idea behind this project was to provide an easy way to access validated data and create analytics. This tool has proven highly effective for many of the world's most notable financial services firms. I developed the UI with performance in mind. On the front end, the UI was supported by React and Apollo GraphQL.
Skills
Libraries/APIs
React, Context API, React Router, REST APIs, React Redux, Reselect, Recompose, React Query, Formik, Zod, Lodash, Day.js, RxJS, Immutable.js, Yup, Normalizr, Segment.io, Recharts, Plotly.js, React DnD, Node.js, WebRTC, TanStack Table, React Motion, D3.js, OpenAPI, Playwright, React Testing Library
Tools
JSX, GitHub, Auth0, BrowserStack, Redux Toolkit, Figma, Confluence, Jira, Plotly, Dnd-kit, Shadcn, Lighthouse
Languages
JavaScript, HTML, CSS, ECMAScript (ES6), TypeScript, Sass, HTML5, GraphQL, CSS3
Frameworks
Redux, Next.js, Material UI, Jest, Tailwind CSS, i18next, Cypress, React Native, Ant Design, Bootstrap, Recoil, Express.js
Paradigms
Functional Programming, Unit Testing, Agile Software Development, REST, Agile, Search Engine Optimization (SEO), Web Performance Optimization (WPO)
Platforms
Firebase, LiveKit
Storage
Cloud Firestore
Other
Front-end, React Hooks, API Integration, User Experience (UX), User Interface (UI), Application State Management, APIs, Reusable Libraries, Axios, Enzyme, DOM, Pixel Perfect, Progressive Web Applications (PWAs), PWA, Tailwind UI, Radix UI, Zustand, Storybook, JSDoc, Styled-components, Apollo, PSD to HTML, Code Architecture, Responsive UI, JavaScript Libraries, WCAG 2, Apollo Server, react-easy-crop, Firebase Cloud Functions, Typesense, WebSockets, Web Content Accessibility Guidelines (WCAG), Data Visualization, Web Accessibility, Caching, Web Scalability, Scalability, Core Web Vitals, Static Site Generators, Front-end Architecture, Server-side Rendering (SSR), SSG, Accessibility, Chrome DevTools, Lazy Loading, Startups, Cursor AI, UI Motion
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