César is available for hire
Hire CésarCésar Antunes
Verified Expert in Engineering
Front-end Developer
Belo Horizonte - State of Minas Gerais, Brazil
Toptal member since June 1, 2020
Bio
César has four years of experience as a professional front-end developer. His expertise includes Angular, React, .NET, and other frameworks. César's current focus is on React and its latest features and tools, including TypeScript, Sass, Enzyme, Cypress, and Next.js.
Portfolio
Plank
JavaScript, TypeScript, Node.js, React, React Native, Expo, Tailwind CSS, Axios...
meutudo.
JavaScript, TypeScript, React, React Native, Redux, Redux-Saga...
AtomicVest Inc
TypeScript, React, SQL, CSS, HTML, Tailwind CSS, JavaScript, LaunchDarkly...
Experience
- JavaScript - 7 years
- React - 5 years
- TypeScript - 5 years
- CSS - 4 years
- HTML - 4 years
- React Native - 3 years
- Redux - 2 years
- Next.js - 1 year
Work Experience
Senior Full-stack Developer
2024 - PRESENT
Plank
- Led and developed and app that connects to a physical health monitoring device via Bluetooth, send metrics to the backend and display processed metrics as graphs, using React Native with Expo, Typescript and Native Wind.
- Developed an API using Express, Prisma, and PostgreSQL, following the Clean Architecture principles. Led and developed an app that connects to a physical health monitoring device via Bluetooth, sends metrics to the back end, and displays processed metrics as graphs, using React Native with Expo, TypeScript, and NativeWind.
- Integrated the app and Auth0 using Auth0 Management API through our own API.
Technologies: JavaScript, TypeScript, Node.js, React, React Native, Expo, Tailwind CSS, Axios, Express.js, Auth0, Auth0 API, Supabase, PostgreSQL, Prisma, Full-stack, REST APIs, Web Development, Mobile Development, Mobile App Development
Senior Front-end Developer
2023 - 2024
meutudo.
- Maintained and improved the main company's mobile app using React Native, TypeScript, and Redux and testing using Jest and React Testing Library.
- Led the junior front-end developers of the team by helping them improve technically, keeping track of their contributions, and ensuring code quality and reliability.
- Architected, led, and maintained the company's component library, using the same codebase in the React Native mobile app and React web applications. Led junior main contributors of the library and designed best practices for external contributors.
Technologies: JavaScript, TypeScript, React, React Native, Redux, Redux-Saga, Styled-components, GitHub Actions, Lerna, React Testing Library, Jest
Front-end Developer
2022 - 2023
AtomicVest Inc
- Maintained and improved an embedded app for investment and shares market, using React, TypeScript, and modern tools to convert Figma files into screens/components.
- Created a Node.js SDK based on an OpenAPI schema JSON file. The library generates all the code by the schema file using Axios and typed methods. Developed a workflow that automatically updates the version every time the schema file gets updated.
- Converted an old dashboard web app from Next.js to React using the most recent technologies.
Technologies: TypeScript, React, SQL, CSS, HTML, Tailwind CSS, JavaScript, LaunchDarkly, Auth0, Amazon S3 (AWS S3), Front-end, Figma, Koa, Next.js, Node.js, D3.js
Front-end Developer
2021 - 2022
BILDIT
- Maintained and improved the company's CMS dashboard web application using Jira as a reporting tool.
- Migrated JavaScript code to TypeScript, which included mapping all data types and replacing React PropTypes with TypeScript types.
- Improved the performance of the data table pages by implementing pagination in the back-end side and transferring filter and ordering logic from the front end to the back end.
- Proposed a new pattern to define Redux's actions and reducers which rendered it simpler and more type-safe and more appropriate for the new TypeScript environment.
Technologies: JavaScript, TypeScript, React, Redux, Sagas, Node.js, Firebase, React Native, HTML5, CSS, HTML, Front-end
Front-end Developer
2021 - 2021
Belk
- Contributed to the refactoring of the eCommerce app from native code to a single React Native project.
- Proposed new architecture types and code organization techniques to improve code quality regarding navigation, forms, and UI elements.
- Developed performance improvements in the product list which removed 80% of app crashes on this screen.
Technologies: React Native, Redux, TypeScript, Sagas, Yup, React Redux Form, Bitrise, CocoaPods, Swift, Java, Node.js, JavaScript, React, Bitbucket, Git, Postman, Reactotron, CSS, Front-end
Freelance Developer
2020 - 2021
Freelance
- Worked on a music mobile app, using React and Ionic, and later refactored it to React Native. The app was written in TypeScript, using Redux-saga and Video.js.
- Developed an npm package to manage the UI elements of a company. The work involved refactoring the React components, from JavaScript to TypeScript and from Sass to Emotion CSS, and migrating their implementation to an npm package.
- Worked as a front-end developer on a mobile shop app using React Native, TypeScript, and Redux-saga.
Technologies: React, React Native, TypeScript, Sass, Storybook, Redux, Redux Thunk, Sagas, Video.js, Redux-Saga, JavaScript, CSS, HTML, Front-end
Front-end Developer
2019 - 2021
Hotmart
- Developed SPAs using React, TypeScript, Sass, and Redux, and the newest features of React such as Hooks, memo, refs, and the Context API.
- Created forms using React, Yup, and React Hook Form.
- Developed React component libraries using React, TypeScript, and Sass, and published them in Hotmart's private NPM repository.
- Improved the browser performance of a chat web component, using React component memoization, list virtualization, and event throttling using Lodash.
- Rewrote a Node.js server application using Socket.IO. The previous implementation had several memory leaks and performance issues. A new module architecture solved the problem.
- Completed end-to-end tests using Cypress, and included this as a step in continuous deployment using Drone.
Technologies: NPM, Drone CI, Enzyme, Cypress, Redux Thunk, GitHub, Webpack, Sass, Redux, Socket.IO, Node.js, Git, React, TypeScript, JavaScript, CSS, HTML, Front-end
Front-end Developer
2016 - 2019
Usemobile
- Developed admin dashboards for mobility apps, using AngularJS.
- Built a module to monitor a driver's position and route, using JavaScript and Google Maps API.
- Developed websites using .NET Framework and built a search module for school buildings that uses text as the region, using JavaScript and Google Maps API.
- Created a desktop application using AngularJS and Electron.js.
Technologies: Git, Electron, .NET, Node.js, React, AngularJS, JavaScript, CSS, HTML, Front-end, Google Maps, Adobe Experience Design (XD), Firebase
Game Developer
2014 - 2015
Meatballs Digital Brunch
- Developed a game using Unity3D. Users could access the game through a webpage and product key, and the game was controlled by the webpage using WebSockets.
- Created an animation to run in Oculus Rift using Unity3D.
- Built an AR application using Unity3D to preview a neighborhood mockup while pointing the device camera to the company logo.
Technologies: C#, Blender, Unity3D, Photoshop CS5, WebSockets, RPC, Game Development
Project History
Portal Web Page for Kumon Schools
A server-side rendering web page, using the .NET Framework to present the Kumon school. I developed this web page, which includes details about the courses, a blog page, a Google Maps nearby search for the schools, and six different languages.
Front-end of Lyra Music App (via Toptal)
A Persian music app, for which I was the front-end developer. The tech stack was React, TypeScript, and Redux-saga, and hybrid development was done with Ionic, which we later changed to React Native. I co-developed the front end of the mobile web app, which is a Spotify-like music player, using React, TypeScript, Ionic, Redux, and Sagas. I also migrated the mobile app and all its UI components from React and Ionic to React Native.
Front-end Development at Strive Talent, Inc. (via Toptal)
Key Accomplishments:
• Updated the style of the components following the design provided by the client.
• Converted React components from JavaScript to TypeScript, creating useful types and interfaces and proposing good practices.
• Converted React component styles from Sass to Emotion CSS.
• Updated the style of the components following the design provided by the client.
• Converted React components from JavaScript to TypeScript, creating useful types and interfaces and proposing good practices.
• Converted React component styles from Sass to Emotion CSS.
Education
2015 - 2019
Bachelor's Degree in Computer Science
Federal University of Ouro Preto - Ouro Preto, Minas Gerais, Brazil
2011 - 2014
Bachelor of Technology Degree in Game Development
Pontifical Catholic University of Minas Gerais, PUC-MG - Belo Horizonte, Minas Gerais, Brazil
Skills
Libraries/APIs
React, Node.js, Socket.IO, Google Maps, Emotion Library, MobX, Yup, React Redux Form, CocoaPods, Redux-Saga, D3.js, React Testing Library, Auth0 API, REST APIs
Tools
Blender, GitHub, Git, Sublime Text, Postman, Webpack, CircleCI, NPM, Redux Thunk, Figma, Bitbucket, Reactotron, LaunchDarkly, Auth0, Photoshop CS5, Adobe Experience Design (XD), Lerna, Expo, Prisma, Claude Code
Languages
JavaScript, TypeScript, CSS, HTML, HTML5, Sass, SCSS, C#.NET, C#, Swift, Java, SQL, GraphQL
Frameworks
Unity3D, Redux, AngularJS, Cypress, React Native, Next.js, Electron, Chrome, .NET, Jest, Ionic, Ionic 3, Video.js, Tailwind CSS, Koa, Material UI, Express.js
Paradigms
Kanban, Mobile Development
Platforms
Drone CI, Visual Studio Code (VS Code), Windows, Heroku, Linux, MacOS, Bitrise, Firebase
Storage
Amazon S3 (AWS S3), PostgreSQL
Other
Front-end, Enzyme, i18n, Sagas, Storybook, Computer Science, Game Development, Multilingual Websites, CSS Modules, WebSockets, RPC, Styled-components, GitHub Actions, Axios, Supabase, Full-stack, Web Development, Mobile App Development, Cursor AI
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