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Nicolas Malezh
Verified Expert in Engineering
Front-end Developer
Lisbon, Portugal
Toptal member since May 9, 2022
Bio
Nicolas is a senior front-end engineer who has strong experience building bug-free, performant, and user-friendly mobile and web applications from scratch to production. His clients were well-known American organizations like NFL and Cox Automotive. Nicolas is a leader who has managed development teams and created project architecture. He expresses his passion for programming by participating in knowledge-sharing sessions, developing student learning guides, and mentoring.
Portfolio
Thera Inc.
JavaScript, TypeScript, React Native, Realm, Firebase, Jest, Amplitude...
Bilt Technologies Inc
React, Redux, User Interface (UI), TypeScript, Next.js, JavaScript, GraphQL...
Make Disciples Charitable Foundation
React Native, React, Design Systems, User Interface (UI), User Experience (UX)...
Experience
- Front-end - 10 years
- JavaScript - 10 years
- React - 9 years
- TypeScript - 8 years
- Redux - 8 years
- React Native - 8 years
- Realm - 5 years
- Firebase - 5 years
Preferred Environment
MacOS
The most amazing...
...product I've developed is my startup. A mental health mobile app called Thera. It helps thousands of people to increase their emotional intelligence.
Work Experience
React Native Developer
2019 - 2025
Thera Inc.
- Built a React Native mobile application used daily by thousands of people.
- Implemented AI features using OpenAI API to help users understand their emotions better.
- Created a cross-platform React Native mobile application that is indistinguishable from a native mobile app from a user's perspective.
- Oversaw all the steps of implementation of the mobile app, from design and development to deployment.
- Implemented a low-cost infrastructure of the app using serverless technologies.
- Designed a secure and fast user data storage solution using an offline-first database.
- Implemented an in-app purchases functionality that works stable across the platform with UX in mind.
- Implemented an analytics infrastructure that allows understanding of user behavior with high accuracy and stays confidential for users.
- Improved the app's rating by implementing an algorithm that asks users to rate the app only after certain interactions with it.
- Designed an infrastructure that helps to easily test hypotheses with A/B tests using Firebase and Amplitude.
Technologies: JavaScript, TypeScript, React Native, Realm, Firebase, Jest, Amplitude, AppsFlyer, Fastlane, Android, iOS, CSS, React, Redux, OpenAI, Front-end Development, Front-end, Figma, APIs, User Experience (UX), User Interface (UI), REST APIs, UX Design, Mobile, ChatGPT, Large Language Models (LLMs), Artificial Intelligence (AI), Firebase Cloud Messaging (FCM), Firebase Cloud Functions, Firebase Analytics, OpenAI API
Front-end Developer
2024 - 2024
Bilt Technologies Inc
- Implemented core components for the website application.
- Updated existing modules to match current best practices, improving the website's performance.
- Improved animations of website navigation components.
Technologies: React, Redux, User Interface (UI), TypeScript, Next.js, JavaScript, GraphQL, UI Development
React/React Native Developer
2023 - 2023
Make Disciples Charitable Foundation
- Built a well-structured and high-quality front-end codebase from scratch, successfully taking it through to production.
- Implemented the app's primary feature, a user-friendly interactive map for community discovery, ensuring high visual quality and adherence to Figma design specifications.
- Created an infrastructure for health monitoring and user behavior analytics.
Technologies: React Native, React, Design Systems, User Interface (UI), User Experience (UX), Mobile App Design, Mobile Design, Figma, UI Design, GraphQL, UI Maps, Google Maps, Google Maps SDK, Mobile, Front-end, Front-end Development
React Native Developer
2022 - 2022
PepsiCo Global - PepsiCo IT Services
- Upgraded the standing codebase to the latest standards.
- Fixed bugs across different platforms, including web and mobile.
- Helped with the build deployments for different environments.
Technologies: React Native, React, Redux, JavaScript, HTML, CSS, Front-end, Front-end Development, APIs, User Interface (UI), Mobile
Senior Front-end Developer and Architect
2020 - 2021
ScienceSoft
- Found architecture flaws in the current front-end implementation of a React web application, which would make the codebase impossible to scale. Initialized discussion regarding this issue and was assigned to implement a new codebase.
- Created a stable and scalable architecture for a React web application from scratch. The new architecture was easy to use, so the speed of implementation of new features was very high.
- Implemented all authentication features of the front-end side of a React web application.
- Led the client-side development of a React app managing five front-end developers.
- Estimated the time of features implemented on the client-side by a team with very high accuracy.
Technologies: JavaScript, TypeScript, React, React Native, Jest, iOS, Android, Ant Design, CSS, Redux, Front-end, Front-end Development, Figma, APIs, User Experience (UX), User Interface (UI), REST APIs, Mobile
Senior Front-end Developer and Tech Lead
2017 - 2019
iTechArt
- Worked with well-known American organizations and companies like NFL and Cox Automotive.
- Led a client-side development of a React Native mobile app, managing four front-end developers.
- Participated in the knowledge-sharing sessions of the company.
- Created internal React Native courses for students of the company.
- Mentored a junior React Native developer that was able to work on a project with the efficiency of a middle developer in one month of training.
- Worked on mobile and web applications of NFL used by millions of users every day.
Technologies: JavaScript, TypeScript, React Native, Redux, MobX, GraphQL, Jest, iOS, Android, Expo.io, CSS, React, Front-end, Front-end Development, APIs, User Interface (UI), REST APIs, Mobile
Front-end Developer
2016 - 2017
Omertex
- Implemented an architecture for a project that required a shared codebase between React and React Native applications.
- Led the client-side development of a React Native mobile app, managing three front-end developers.
- Implemented the integration between React components and the D3 library for displaying interactive charts.
Technologies: JavaScript, TypeScript, React, React Native, Redux, MobX, D3.js, iOS, Android, Node.js, CSS, Front-end, Front-end Development, APIs, User Interface (UI), REST APIs, Mobile
Web Developer
2014 - 2016
Freelance
- Created a website for a finance company entirely from scratch, including prototyping, design, front-end implementation, and integration with CMS.
- Developed modern landing pages with adaptive, mobile-first layouts.
- Integrated websites with different CMS systems such as Joomla, WordPress, and Drupal.
Technologies: HTML, jQuery, CSS, User Interface (UI), Front-end, Front-end Development
Experience
JoyProject | Charity Project for Religious Nonprofit Organization
https://apps.apple.com/us/app/joyproject/id6468271294JoyProject is a charitable mobile application for a religious organization. This app is designed to bring together religious people and those committed to altruistic values, enabling them to share goods, participate in giveaways, and meet others with similar interests. Written in React Native, the app offers a responsive and engaging user interface while utilizing GraphQL for back-end operations to ensure efficient data handling and server interactions. The primary goal is to foster a sense of community and encourage charitable acts within the religious community.
Thera | A Mental Health Mobile Application
https://apps.apple.com/us/app/id1474161008Thera is a mental health application that helps people increase their emotional intelligence and have a happier life by better understanding their emotions.
The app was downloaded more than 100,000 times and had a user base of 10,000 monthly active users.
Responsibilities as a CTO
• Thinking of new features that can improve users' lives and implementing them in the mobile app.
• Building a high performant and user-friendly UI.
• Implementing technical solutions that help make better business decisions.
• Monitoring potential issues in the app and preventing new bugs.
• Ensuring that implemented technical solutions are secure, don't violate users' privacy, and keep users' sensitive data safe.
• Participating in business processes, generating ideas, and defining the technical approaches.
The app was downloaded more than 100,000 times and had a user base of 10,000 monthly active users.
Responsibilities as a CTO
• Thinking of new features that can improve users' lives and implementing them in the mobile app.
• Building a high performant and user-friendly UI.
• Implementing technical solutions that help make better business decisions.
• Monitoring potential issues in the app and preventing new bugs.
• Ensuring that implemented technical solutions are secure, don't violate users' privacy, and keep users' sensitive data safe.
• Participating in business processes, generating ideas, and defining the technical approaches.
NFL | A Website and Mobile Application
https://apps.apple.com/us/app/nfl/id389781154The National Football League (NFL) is a professional American football league, one of the four major professional sports leagues in North America and the world's highest professional level of American football.
It’s the biggest and most valuable site related to the American football topic and its mobile application with more than 50 million user downloads. Their site and mobile application host different content, including news, videos, events, life, and translations.
Responsibilities
• Implementing different UI components, pages, and screens.
• Improving business logic for authentication processes.
• Researching and integrating different third-party modules.
• Refactoring
• Code reviewing
It’s the biggest and most valuable site related to the American football topic and its mobile application with more than 50 million user downloads. Their site and mobile application host different content, including news, videos, events, life, and translations.
Responsibilities
• Implementing different UI components, pages, and screens.
• Improving business logic for authentication processes.
• Researching and integrating different third-party modules.
• Refactoring
• Code reviewing
Manheim Express, Cox Automotive
The project is dedicated to developing an innovative product for the transport industry. The product is specially designed to provide car sellers with specific recommendations on how to price vehicles most accurately, recondition the cars, and best distribute them across physical wholesale auctions.
With over 40,000 auto dealer clients across five continents, Cox Automotive strives to understand users’ needs by pairing their insights and research with their business goals, delivering inspired results to bridge the gap between consumers, manufacturers, dealers, and lenders at every stage of the automotive experience.
Responsibilities
• Implementing a core front-end architecture.
• Integrating third-party modules.
• Setting up a convenient development environment and tools.
• Communicating actively with the scrum master and customer.
• Code reviewing
• Team-leading and mentoring
With over 40,000 auto dealer clients across five continents, Cox Automotive strives to understand users’ needs by pairing their insights and research with their business goals, delivering inspired results to bridge the gap between consumers, manufacturers, dealers, and lenders at every stage of the automotive experience.
Responsibilities
• Implementing a core front-end architecture.
• Integrating third-party modules.
• Setting up a convenient development environment and tools.
• Communicating actively with the scrum master and customer.
• Code reviewing
• Team-leading and mentoring
Certifications
MAY 2019 - PRESENT
Flutter Create
Skills
Libraries/APIs
React, REST APIs, Redux Persist, React Query, React Router, Moment.js, React Navigation, OpenAI API, jQuery, MobX, D3.js, Redux-Saga, React Hook Form, Node.js, Ramda, Google Drive API, Google Maps, Google Maps SDK
Tools
Fastlane, Flow, Firebase Analytics, Firebase Authentication, Firebase Cloud Messaging (FCM), Expo.io, Figma, ChatGPT
Languages
HTML, CSS, JavaScript, TypeScript, GraphQL
Frameworks
React Native, Redux, Ant Design, Jest, Flutter, Next.js
Platforms
Mobile, Firebase, MacOS, AppsFlyer, Android, iOS
Paradigms
Offline-first Development, UX Design, Mobile App Design, Mobile Design, UI Design, Responsive Web Design (RWD)
Storage
Realm, NoSQL, Firebase Realtime Database
Other
Front-end Development, Front-end, APIs, User Interface (UI), Internalization, Mobile UX, In-app Purchases, User Experience (UX), Amplitude, Firebase Cloud Functions, Biometrics, Data Encryption, OpenAI, Design Systems, UI Maps, UI Development, Large Language Models (LLMs), Artificial Intelligence (AI)
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