Publication
Building Simple and Efficient Components With React-Bootstrap
https://www.toptal.com/developers/bootstrap/react-bootstrap-components
Matej is available for hire
Hire MatejMatej Bilić
Verified Expert in Engineering
React Developer
Bošnjaci, Croatia
Toptal member since November 4, 2021
Bio
Matej is a talented full-stack web developer and mobile application developer adept at advanced web and application development stages. He is knowledgeable in a variety of technologies, including React, React Native, Firebase, Express, Django, and many others. Matej can effectively self-manage while working on independent projects, as well as collaborate in a team setting.
Portfolio
Hippo Technologies LLC
React, HTML, JavaScript, CSS, Node.js, SEO Tools, Contentful, TypeScript...
Back Intelligence LLC
React Native, HTML, CSS, JavaScript, Node.js, API Integration, Claude Code...
Breezi Inc.
JavaScript, React Native, Tailwind CSS, Expo, iOS, MongoDB, Node.js, GraphQL...
Experience
- React - 9 years
- React Native - 8 years
- PostgreSQL - 7 years
- TypeScript - 5 years
- REST APIs - 3 years
- Firebase - 2 years
- GraphQL - 2 years
- Django - 2 years
Preferred Environment
Windows, Ubuntu, Vim Text Editor, Visual Studio Code (VS Code), MacOS
The most amazing...
...things I’ve developed are a website and an application for a company that creates adventures in various cities, which supersede tourist guides.
Work Experience
Front-end Developer
2023 - PRESENT
Hippo Technologies LLC
- Rebuilt large parts of the app using React and Next.js, including drug pages, search, and coupon flows.
- Implemented a new GraphQL-based data layer, replacing legacy REST calls and simplifying data management.
- Reworked the entire Contentful setup: built reusable schemas, migrated data, and optimized content delivery.
- Developed a partner-specific version of the app for Yahoo with branding, routing, and layout adjustments.
- Integrated historical pricing charts using Recharts, tied to feature flags and responsive UI.
- Refactored ZIP code and prescription logic for better accuracy and maintainability.
- Contributed to a full SEO overhaul: custom sitemaps, canonical tags, robots.txt logic, and meta data handling.
- Built responsive layouts and components using styled-components.
- Improved test coverage to enforce code quality standards across the codebase.
Technologies: React, HTML, JavaScript, CSS, Node.js, SEO Tools, Contentful, TypeScript, GraphQL, Grafana, Prometheus, Styled-components, Cypress, Playwright, Jest, AWS IAM, Cookies, Express.js, React Helmet, Lodash, MobX, Next.js, Dotenv, ESLint, Factory, OpenAI, Sitemaps, Recharts, Health, Healthcare, ETL, Web Scraping, Data Integration, Performance Optimization, Scalability, Shadcn, Hash, Cryptography, Deterministic Encryption, Vercel, Web App Deployment, Claude Code, Cursor AI, Data Aggregation, UI Design, UX Design, GPS, Front-end Development, Accessibility, Back-end Development, Web App Development
Full-stack Mobile Developer
2025 - 2025
Back Intelligence LLC
- Organized project structure and led task planning with the client.
- Fixed critical bugs and improved overall app stability and performance.
- Reduced video load time from 3.8s to 0.4s (Mux and AWS Lambda) and resolved buffering.
- Built and released Android app; managed App Store and Play Store submissions.
- Upgraded and maintained core tech stack (Expo SDK, ESLint, tooling).
- Added build, release, and store submission automation.
- Implemented a complete authentication system with subscription transfer support.
- Built and maintained back-end integrations (Firestore, RevenueCat, Newsletter).
- Ensured subscription consistency, limits, and reliable push notifications.
- Improved onboarding, UI responsiveness, app startup logic, and lifecycle UX.
Technologies: React Native, HTML, CSS, JavaScript, Node.js, API Integration, Claude Code, Cursor AI, Mobile UI, Product Owner, Data Aggregation, UI Design, UX Design, React Navigation, Mobile App Development, Push Notifications, Front-end Development, Accessibility, Back-end Development, App Store
Full-stack Developer
2025 - 2025
Breezi Inc.
- Built and maintained key features using React Native and Expo.
- Designed dynamic UI components with Tailwind CSS, optimized for both iOS and Android.
- Collaborated with designers and back-end developers to implement end-to-end functionality.
- Ensured high app performance and responsiveness through optimization and testing.
- Wrote reusable components with TypeScript to improve maintainability and reduce bugs.
- Participated in code reviews and maintained high code quality standards.
- Integrated platform-specific behavior and mobile-native modules.
- Worked with back-end APIs and GraphQL for efficient data fetching.
Technologies: JavaScript, React Native, Tailwind CSS, Expo, iOS, MongoDB, Node.js, GraphQL, Cross-platform App Development, Data Integration, Performance Optimization, Scalability, Mobile Apps, Vercel, Web App Deployment, Mobile UI, Data Aggregation, UX Design, React Navigation, Mobile App Development, Push Notifications, Front-end Development, Accessibility, Back-end Development, App Store, Web App Development
Full-stack Engineer
2022 - 2023
Bicycle
- Specialized in data visualization and worked with big data as a front-end developer.
- Leveraged expertise in Apollo GraphQL, React, and REST API to create insightful charts for clients that improved optimization and reduced loading times.
- Developed complex visualizations, including tree diagrams and Sankey diagrams, to help clients better understand their big data sets.
- Provided valuable insights that drove business decisions and improved client outcomes.
- Contributed to a team environment focused on collaboration, innovation, and excellence in client service.
Technologies: JavaScript, TypeScript, React, Data Visualization, Web Applications, SaaS, D3.js, Big Data, Large-scale Distributed Systems, Node.js, React Native, Full-stack, Visualization, Visualization Tools, API Development, APIs, Material UI, Charts, Application State Management, Data Integration, Performance Optimization, Scalability, Data Aggregation, UI Design, UX Design, Front-end Development, Accessibility, Back-end Development, Web App Development
Back-end Engineer
2022 - 2022
Legion Health, Inc.
- Developed the back-end to implement payouts using Stripe, significantly reducing the time it takes to pay the users.
- Automated payments by creating a GraphQL endpoint that automatically calculates the amount owed to the user and pays them.
- Worked both within a team and independently to achieve the client's goals.
- Communicated effectively with team members to plan out the database structure and to achieve the optimal solution for automated payouts.
- Ensured the endpoint, payouts, and transactions were safe and secure.
Technologies: Node.js, Stripe, API Integration, APIs, Digital Payments, REST APIs, GraphQL, Apollo, React Apollo, Apollo Server, Prisma, PostgreSQL, JSON, Bug Fixes, Code Review, REST, Collaboration, Real-time Data, Databases, Marketplace Platforms, B2B, SaaS, Web Development, Figma, Web Dashboards, Online Payments, Web Applications, API Development, Webhooks, Application State Management, Scalability, Data Aggregation, Back-end Development, Web App Development
QA Automation Engineer
2021 - 2022
Veza (via Toptal)
- Designed and implemented automated tests and scripts using Cypress.
- Caught numerous errors in every PR before they got merged with the main branch.
- Migrated previously existing tests from Nightwatch.js to Cypress.
Technologies: TypeScript, JavaScript, JavaScript Testing, Jira, GitHub, Data Sourcing, Web Security, Asynchronous Data Streams, Cypress, Nightwatch.js, Testing, UI Testing, QA Testing, Automation, UI Automation, QA Automation, Test Automation, Docker, Jest, API Integration, REST APIs, JSON, Bug Fixes, Code Review, REST, Collaboration, Real-time Data, SaaS, Web Development, Cloud Storage, Automated Testing, Amazon Web Services (AWS), Azure, Puppeteer, Chromium, Web Dashboards, Cloud Platforms, Web Applications, Big Data, Data Visualization, Visualization, Visualization Tools, Application State Management, Performance Optimization, Data Aggregation, Front-end Development, Back-end Development, Web App Development
Freelance Full-stack Developer
2019 - 2021
An Online Freelance Agency
- Worked efficiently and organized work to complete assignments on time.
- Troubleshot and remediated web applications efficiently.
- Integrated databases, authentication, and data storage to web applications.
- Developed, tested, deployed, and maintained web applications.
- Utilized the latest web technologies to solve complex problems.
- Improved the user experience through web applications by designing and modifying existing user interfaces.
Technologies: React, React Native, JavaScript, TypeScript, HTML, CSS, Sass, Python 3, Programming, Firebase, Django, GraphQL, Express.js, Node.js, REST APIs, Bootstrap, Deck.gl, i18n, Formik, Expo, React-Bootstrap, Jest, Git, NPM, TypeORM, MySQL, PostgreSQL, Draft.js, Stripe API, Stripe Checkout, Stripe Subscriptions, Lodash, Mapbox GL, Front-end, Web Architecture, Architecture, API Integration, APIs, Chart.js, MongoDB, Tailwind CSS, Serverless, Redux, JSON Web Tokens (JWT), Responsive Web Apps, Expo.io, D3.js, JSON, Bug Fixes, Code Review, Full-stack, Dashboards, NoSQL, Mobile, REST, Collaboration, Real-time Data, Agile Product Delivery, Databases, Elasticsearch, Marketplace Platforms, Contentful, React Redux, Web Development, Mobile Development, Cloud Storage, Full-stack Development, UI Development, User Experience (UX), User Interface (UI), Minimum Viable Product (MVP), Figma, Design Systems, Charts, Puppeteer, Chromium, Web Dashboards, Behavior-driven Development (BDD), Firebase Authentication, Webpack, Online Payments, Cloud Platforms, Authentication, Mapbox, Google Maps, Mapbox SDK, Google Maps SDK, Data Visualization, Web Applications, Content Management Systems (CMS), Visualization, Visualization Tools, API Development, Webhooks, SEO Tools, Search Engine Optimization (SEO), Application State Management, Stripe Payments, Data Integration, Performance Optimization, Scalability, Mobile Apps, Vercel, Redis, Supabase, Web App Deployment, Mobile UI, Product Owner, Data Aggregation, UI Design, UX Design, React Navigation, Sentry, Mobile App Development, GPS, Push Notifications, Front-end Development, Accessibility, Back-end Development, App Store, Web App Development
Full-stack Developer
2019 - 2019
An Online Freelance Agency
- Contributed to the development of company objectives and worked to achieve them.
- Designed, coded, and tested solutions in collaboration with others.
- Achieved successful software modifications and alterations based on specific design specifications.
- Stayed on top of new trends, technologies, and standards in website development.
- Used uniform fonts, formatting, images, and layout, and achieved a consistent look and visual theme for each website.
- Ensured client deadlines were met, demonstrated excellent decision-making abilities, and used problem-solving skills effectively.
Technologies: React, React Native, Firebase, Django, Web Architecture, Architecture, HTML, CSS, JavaScript, TypeScript, Data, Auth, SQL, SQLite, MySQL, Admin Panels, API Integration, REST APIs, APIs, Tailwind CSS, Serverless, Redux, JSON Web Tokens (JWT), Responsive Web Apps, Expo.io, D3.js, JSON, Bug Fixes, Code Review, Full-stack, Dashboards, NoSQL, Mobile, REST, Collaboration, Real-time Data, Agile Product Delivery, Databases, Elasticsearch, Marketplace Platforms, Contentful, React Redux, Web Development, Mobile Development, Cloud Storage, Full-stack Development, UI Development, User Experience (UX), User Interface (UI), Minimum Viable Product (MVP), Figma, Design Systems, Charts, Puppeteer, Chromium, Web Dashboards, Behavior-driven Development (BDD), Firebase Authentication, Webpack, Online Payments, Cloud Platforms, Authentication, Mapbox, Google Maps, Mapbox SDK, Google Maps SDK, Data Visualization, Web Applications, Visualization, Visualization Tools, API Development, Webhooks, SEO Tools, Search Engine Optimization (SEO), Application State Management, Stripe Payments, Data Integration, Performance Optimization, Scalability, Mobile Apps, Vercel, Redis, Supabase, Web App Deployment, Mobile UI, Product Owner, Data Aggregation, UI Design, UX Design, React Navigation, Sentry, Mobile App Development, GPS, Push Notifications, Front-end Development, Accessibility, Back-end Development, App Store, Web App Development
Motion Graphics Expert
2014 - 2018
An Online Freelance Agency
- Developed motion graphics to enhance the design of websites.
- Ensured that motion graphics were used to support specific storytelling requirements.
- Animated characters using advanced software to place cartoons into motion.
- Produced instructional videos used to train employees.
- Produced marketing videos to increase the number of sales for businesses.
Technologies: After Effects CC, Illustrator CC, Photoshop CC, Blender
Graphic Designer
2014 - 2018
An Online Freelance Agency
- Designed and developed materials to improve the design, appearance, and UI of websites.
- Worked alongside marketing specialists and graphic designers.
- Completed many freelance graphic design projects with a high customer satisfaction rate.
- Contributed to the creation of graphic materials for use by the marketing department.
Technologies: Photoshop CC, Illustrator CC, Blender
Experience
Web App from Which Users Can Obtain Inbound Leads
A React application that lets users register and quickly create profiles, showcasing their skills and experiences.
I developed the website's front-end, added database, storage, authentication, and monthly subscriptions as a full-stack developer. Using a web designer's design, I implemented it on the website, but I also made creative decisions.
I developed the website's front-end, added database, storage, authentication, and monthly subscriptions as a full-stack developer. Using a web designer's design, I implemented it on the website, but I also made creative decisions.
React App for Adventures in Various Cities
This is a React app that allows users to explore various cities across the globe without the need for a tourist guide.
It was a full-stack project that I worked on alone. I was responsible for creating a website where users could view and purchase adventures, login, register, and edit their profiles. My job also included creating a tool that the client could use to create new adventures, send newsletters, manage users and promote users to administrators. The adventure creation tool needed to meet a variety of requirements, such as tracking the user's location and determining the shortest route to the location the adventure creator had chosen. The website needed to be in two languages.
It was a full-stack project that I worked on alone. I was responsible for creating a website where users could view and purchase adventures, login, register, and edit their profiles. My job also included creating a tool that the client could use to create new adventures, send newsletters, manage users and promote users to administrators. The adventure creation tool needed to meet a variety of requirements, such as tracking the user's location and determining the shortest route to the location the adventure creator had chosen. The website needed to be in two languages.
React Native Mobile App for Adventures in Various Cities
This was the second part of the "React App for adventures in various cities" project.
My task was to develop a mobile app where users could purchase adventures and play. Additionally, they had to be able to log in and register with the same credentials as on the website. The project required me to handle location tracking, app permissions, and local storage. It also had to be compatible with iOS and Android devices and work in two languages.
My task was to develop a mobile app where users could purchase adventures and play. Additionally, they had to be able to log in and register with the same credentials as on the website. The project required me to handle location tracking, app permissions, and local storage. It also had to be compatible with iOS and Android devices and work in two languages.
Django App for Adventures in Various Cities
A Django app for exploring cities around the world using pre-built adventures.
Eventually, React and Firebase were used to redesign this app, but the client initially requested a low-cost website for displaying their adventures, which were created using ChatBot. A Linode Ubuntu server hosted the website, and the adventures were stored in a MySQL database. The website allowed users to register and log in, along with making purchases using Stripe Checkout.
Eventually, React and Firebase were used to redesign this app, but the client initially requested a low-cost website for displaying their adventures, which were created using ChatBot. A Linode Ubuntu server hosted the website, and the adventures were stored in a MySQL database. The website allowed users to register and log in, along with making purchases using Stripe Checkout.
Next.js Portfolio Website
A designer's portfolio website built with Next.js and TypeScript.
They needed to display their past work and case studies on the website, with images displayed in a gallery format, and to have the ability to add new items to the portfolio and modify the existing ones. Additionally, they needed to be able to write new articles and place them in predefined categories. I was required to create a form through which potential clients could inquire about the designer's services.
They needed to display their past work and case studies on the website, with images displayed in a gallery format, and to have the ability to add new items to the portfolio and modify the existing ones. Additionally, they needed to be able to write new articles and place them in predefined categories. I was required to create a form through which potential clients could inquire about the designer's services.
Education
2015 - 2020
Bachelor's Degree in Information Technology and Electrical Engineering
Faculty of Electrical Engineering, Computer Science and Information Technology - Osijek, Croatia
Skills
Libraries/APIs
React, Node.js, REST APIs, D3.js, Formik, Nightwatch.js, API Development, React Navigation, Three.js, Stripe API, Lodash, Mapbox GL, React Motion, Stripe, Mapbox API, Auth, React Native for Web, Chart.js, React Redux, Puppeteer, Google Maps, Google Maps SDK, Yup, Playwright, MobX, Dotenv, Recharts
Tools
NPM, Git, Expo, JSX, JavaScript Testing, GitHub, Expo.io, Figma, Firebase Authentication, Photoshop CC, Illustrator CC, After Effects CC, Blender, Stripe Checkout, react-map-gl, Jira, Prisma, Webpack, Shadcn, Claude Code, Sentry, React Apollo, Grafana, AWS IAM
Languages
JavaScript, TypeScript, HTML, CSS, Sass, SCSS, Markdown, GraphQL, SQL, Python, Python 3
Frameworks
React Native, Bootstrap, Jest, React-Bootstrap, Next.js, Draft.js, Cypress, Django, Express.js, Redux, Tailwind CSS, JSON Web Tokens (JWT), Material UI, Deck.gl
Paradigms
Web Architecture, Test Automation, REST, Mobile Development, Automated Testing, Testing, Automation, Marketplace Platforms, Search Engine Optimization (SEO), UI Design, UX Design, B2B, Behavior-driven Development (BDD), ETL
Platforms
Firebase, EmailJS, iOS, Android, Mobile, Vercel, Ubuntu, MacOS, Contentful, Mapbox, Linode, Docker, Amazon Web Services (AWS), Azure
Storage
JSON, NoSQL, Databases, PostgreSQL, MySQL, SQLite, Database as a Service (DBaaS), Data Integration, MongoDB, Elasticsearch, Redis
Industry Expertise
Healthcare
Other
Programming, i18n, Front-end, UI Testing, UI Automation, API Integration, APIs, Responsive Web Apps, Full-stack, Collaboration, Web Development, Cloud Storage, Full-stack Development, UI Development, User Experience (UX), User Interface (UI), Minimum Viable Product (MVP), Design Systems, Charts, Web Dashboards, Authentication, Web Applications, Application State Management, Cross-platform App Development, Mobile Apps, Web App Deployment, Mobile App Development, GPS, Push Notifications, Front-end Development, Accessibility, Back-end Development, Web App Development, Stripe Subscriptions, CAPTCHA, Asynchronous Data Streams, Architecture, Data, Admin Panels, Web Security, QA Testing, QA Automation, Geolocation, Mapping, QR Codes, Digital Payments, Apollo, Serverless, Bug Fixes, Code Review, Dashboards, Real-time Data, Agile Product Delivery, Chromium, Online Payments, Cloud Platforms, Mapbox SDK, Data Visualization, Content Management Systems (CMS), Visualization, Visualization Tools, Webhooks, SEO Tools, Health, Stripe Payments, Performance Optimization, Scalability, Hash, Cryptography, Deterministic Encryption, Supabase, Cursor AI, Mobile UI, Product Owner, Data Aggregation, App Store, TypeORM, Maps, Google Directions, Google SEO, Data Sourcing, Apollo Server, SaaS, Big Data, Large-scale Distributed Systems, Prometheus, Styled-components, Cookies, React Helmet, ESLint, Factory, OpenAI, Sitemaps, Web Scraping
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.
1
Share your needs
Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2
Choose your talent
Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3
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