Giuseppe Guerra Mongiovi, Developer in São Paulo - State of São Paulo, Brazil
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Giuseppe Guerra Mongiovi

Full-stack Developer

São Paulo - State of São Paulo, Brazil

Toptal member since May 26, 2022

Expertise
Web DevelopmentFull-stackFront EndJavaScriptREST APIReact.jsGitCSSHTML5DatabaseNode.jsExpress.jsTypeScriptAgile Development
Bio

Giuseppe is a full-stack engineer with six years of experience working for gaming, banking, and finance companies. During his studies and early work experiences at one of the world's largest mobile gaming companies, he specialized in full-stack web development using React and Node.js. Giuseppe excels in leading a team and delivering products according to the clients' needs.

Portfolio

Watersabove
React, HTML, CSS, JavaScript, TypeScript, React Native, Node.js
Journey - Main
React, Next.js, Strapi, OpenAI, RESTFul APIs, Node.js, Vercel, Customer.io...
Project 468, Inc (trade name RunWhen)
JavaScript, React, TypeScript, Next.js, Material UI, Axios, Algorithms...

Experience

  • JavaScript - 10 years
  • React - 8 years
  • Full-stack Development - 6 years
  • Web Development - 6 years
  • Node.js - 5 years
  • Software Engineering - 5 years
  • TypeScript - 4 years
  • React Native - 3 years

Preferred Environment

React, Node.js, React Native, TypeScript, REST APIs, JavaScript, HTML, Full-stack, Web Applications, User Experience (UX)

The most amazing...

...thing I’ve done is lead, without prior XML/PHP knowledge, the first XML digital signer in LATAM, enabling cross-border trade, then built an iFood-like app.

Work Experience

Senior Full-stack Engineer (React, Node.js, and React Native)

2025 - 2026
Watersabove
  • Designed and implemented a scalable React-based admin dashboard to manage users, courses, campuses, events, onboarding flows, reported content, forums, and messaging systems, centralizing platform operations and reducing administrative handling time.
  • Built and launched an interactive mobile “Campus” experience featuring biomes, vistas, and spatial rooms, enabling real-time chat, voice communication, and video interaction, supporting concurrent user engagement in immersive virtual environments.
  • Developed and integrated back-end functionality to support dashboard operations, including API endpoints, data validation, and service-layer logic, ensuring reliable data synchronization between front-end systems and core platform services.
Technologies: React, HTML, CSS, JavaScript, TypeScript, React Native, Node.js

Senior Full-stack Engineer

2025 - 2026
Journey - Main
  • Migrated the home page and several highly animated, long-form pages from Webflow into the company’s React application, delivering a pixel-perfect implementation while preserving complex animations and UX details.
  • Built an interstitial app with proper cookie-based authentication between the main Journey web app and booking flow, enabling seamless redirects while preserving selected parameters such as dates, guests, and rooms.
  • Implemented a new Journey Points claim flow, improving reliability, clarity, and overall user experience.
  • Led a major refactor of key web pages (PDPs, HDPs, and RDPs), migrating data fetching from BaseQL to Strapi as Airtable scaled, eliminating performance bottlenecks and improving stability, maintainability, and page speed.
Technologies: React, Next.js, Strapi, OpenAI, RESTFul APIs, Node.js, Vercel, Customer.io, Docker, Google API, Amazon Web Services (AWS), Database Architecture, CI/CD Pipelines, Deployment

Senior Front-end Developer (React)

2024 - 2025
Project 468, Inc (trade name RunWhen)
  • Built an AI chat UI like Cursor.ai with an autocomplete search for scopes and agents. The artifact section shows summaries, tasks, issues for review, and a stats view.
  • Led multiple UI redesigns and UX enhancements across the entire application.
  • Refactored a React Flow map to add subgroups hierarchy, labels on top of each leaf node, or even groups if they have alerts.
  • Created a new VS Code plugin with React from scratch to replicate a part of the web application.
  • Built a suggestions section to recommend the next troubleshooting steps.
Technologies: JavaScript, React, TypeScript, Next.js, Material UI, Axios, Algorithms, React Flow, Deployment

Senior Front-end Developer

2023 - 2023
Nat Inc. DBA Thatch
  • Implemented the entire front-end seller services feature, allowing sellers to sell a consultation call, itinerary, or custom recommendation.
  • Redesigned almost all web pages to match the newly made Figma designs and made them responsive for mobile devices.
  • Refactored the homepage while considering SEO best practices, leading to a 740% increase in people who interacted with the homepage and a 25% increase in the number of people who searched for guides or sellers.
  • Fixed multiple bugs and consistently gave constructive insights and tips for improving the UX and UI.
Technologies: Front-end, React, Pixel Perfect, HTML, CSS, JavaScript, Node.js, TypeScript, Figma, Responsive Web Apps, TypeScript 3, Deployment

Senior Full-stack Developer

2023 - 2023
First Coach Worldwide AB
  • Developed a mobile and web application that enables coaches to free up time so they can focus more on coaching and building their businesses.
  • Refactored the entire web and mobile application and reimplemented all of the pages. Also, refactored the back-end endpoints and most of the database relations.
  • Deployed the back end and front end in the AWS infrastructure, then migrated to DigitalOcean.
  • Integrated with a 3rd-party charts library for both web and mobile to show users' workout progression.
  • Integrated with Stripe to manage payments with the possibility of applying coupons.
Technologies: React Native, React, Node.js, Amazon Web Services (AWS), Xcode, Android Studio, Figma, GitHub, Material UI, REST APIs, Highcharts, Charts, UX Design, Responsive UI, User Experience (UX), MongoDB, DigitalOcean, Pixel Perfect, Database Architecture, CI/CD Pipelines, Deployment

Senior Full-stack Developer

2022 - 2022
Hitch
  • Implemented an entirely new service searching for addresses. With just the address, the user would know how much free money he and his property qualify from the government.
  • Migrated the landing page from Webflow to React and Strapi (CMS).
  • Refactored old equity loan forms flow to improve UX and integrated another third-party API to validate the user's input.
  • Developed A/B testing for new equity loan refactored form flow.
Technologies: Node.js, React, JavaScript, MongoDB, CSS, HTML, Next.js, Sentry, Material UI, TypeScript, Google Analytics, Google Optimize, Content Management Systems (CMS), Webpack, Prisma, Tailwind CSS, Responsive Design, User Experience (UX), Responsive Web Apps, Docker, Customer Relationship Management (CRM), Pixel Perfect, Database Architecture, Deployment

Full-stack Developer

2022 - 2022
Impro.AI, Inc.
  • Implemented primary front-end refactoring to migrate Material-UI to the new version and change all of the stylings to the new SxProps available mixed with style from the material when needed.
  • Cultivated a new achievements tab with a dashboard showing the user's achievements with filters by area or skill. I also implemented multiple pages for the new Super Coach app.
  • Fixed multiple bugs, several of which I discovered.
  • Provided an Azure function that connects to the DB and returns multiple data about a user's achievements. The Azure function is then called in the Google Sheets Script, which populates the sheets whenever the refresh button is clicked.
Technologies: React, Azure, Node.js, TypeScript, GitHub, MobX, NestJS, Material UI, React Hooks, PostgreSQL, Amazon Web Services (AWS), Microservices, Atomic Design, Webpack, HTML, Next.js, APIs, SQL, Full-stack, Web Applications, TypeORM, Serverless, UX Design, Technical Documentation, Documentation, Responsive Design, User Experience (UX), Responsive Web Apps, Docker, Pixel Perfect, Database Architecture, Deployment

Full-stack Engineer

2021 - 2022
Skipify
  • Implemented the merchant OTP checkout flow with Svelte.
  • Fixed multiple bugs in the React-based back office.
  • Started and successfully completed the OTP Svelte project from scratch, with no previous knowledge of the framework.
Technologies: React, Jest, Svelte, TypeScript, Jira, Figma, Git, ESLint, ECMAScript (ES6), Material UI, Styled-components, REST APIs, Express.js, JavaScript, CSS, Front-end, HTML5, Front-end Development, eCommerce, Webpack, HTML, Next.js, APIs, Full-stack, Web Applications, UX Design, Technical Documentation, Documentation, Responsive Design, User Experience (UX), Responsive Web Apps, Pixel Perfect, Database Architecture, Deployment

Full-stack Engineer

2021 - 2021
BEES Bank Brasil
  • Developed multiple microservices with Node.js, Java, and Spring Boot, the main mobile application with React Native, and the back office web applications with React.
  • Implemented the key registration part in the back end with Node.js and user interface in the mobile app with React Native while working in the PIX team.
  • Collaborated with the onboarding team to refactor the onboarding process using the outbox pattern.
Technologies: React, Node.js, React Native, MySQL, MongoDB, Figma, Jest, Jenkins, Git, GraphQL, TypeScript, Styled-components, New Relic, Java, Springbot, Testing, Test-driven Development (TDD), ESLint, ECMAScript (ES6), Spring Boot, REST APIs, Express.js, JavaScript, CSS, Front-end, HTML5, React Redux, Front-end Development, Relational Databases, Atomic Design, eCommerce, Redux, Webpack, HTML, APIs, SQL, Full-stack, Web Applications, Serverless, Amazon Web Services (AWS), UX Design, CI/CD Pipelines, Technical Documentation, Documentation, Material UI, Responsive Design, User Experience (UX), Responsive Web Apps, Docker, Customer Relationship Management (CRM), Pixel Perfect, Database Architecture, PayPal, Stripe, Stripe API, PayPal API, Deployment

Lead Full-stack Engineer

2020 - 2021
Foundation Paraíba Technological Park
  • Led a team of three engineers, one tester, and one designer.
  • Developed end-to-end mobile and web applications focused on the pandemic necessities to minimize human interaction. Clients could scan QR codes from the table and order, but also order through delivery apps such as iFood.
  • Managed a team to implement a digital certificate signer API in PHP.
Technologies: React, Node.js, React Native, MySQL, MongoDB, Jest, Git, Jira, Software Engineering, Testing, Test-driven Development (TDD), Google Cloud, ESLint, ECMAScript (ES6), REST APIs, Express.js, JavaScript, CSS, Front-end, HTML5, React Redux, Front-end Development, Relational Databases, Atomic Design, eCommerce, Webpack, HTML, APIs, SQL, Full-stack, Web Applications, UX Design, Technical Documentation, Documentation, Material UI, Single-page Applications (SPAs), Responsive Design, User Experience (UX), DocuSign, Digital Certificates, Responsive Web Apps, Docker, Pixel Perfect, Database Architecture, PayPal, PHP, PayPal API, CI/CD Pipelines, Deployment

Full-stack Engineer

2019 - 2020
Wildlife Studios
  • Migrated one of the applications to a React and refactored the necessary code for improvements.
  • Investigated and fixed multiple bugs from their main back office.
  • Integrated banners, interstitials, and pop-ups for numerous ad networks, such as Facebook ads, to the existing Waterfall legacy.
Technologies: Node.js, React, MongoDB, TypeScript, Jira, Best Practices, Testing, Test-driven Development (TDD), Full-stack Development, ESLint, Git, REST APIs, Express.js, JavaScript, CSS, Front-end, HTML5, Front-end Development, Redux, Webpack, HTML, APIs, Full-stack, Web Applications, UX Design, Technical Documentation, Documentation, Responsive Design, User Experience (UX), Responsive Web Apps, Pixel Perfect, Database Architecture, Deployment

Full-stack Engineer

2018 - 2019
ASUS
  • Developed a website to manage the development team's Scrum process using React, Node.js, and PostgreSQL.
  • Played a key role as a product manager and scrum master while being a part of the development team.
  • Developed the back office end-to-end using Node.js, MongoDB, and React.
Technologies: React, Angular, Node.js, Java, PostgreSQL, MongoDB, Web Development, Software Engineering, Jira, ESLint, REST APIs, Express.js, JavaScript, CSS, Front-end, HTML5, React Redux, Front-end Development, Relational Databases, Redux, HTML, APIs, Agile, SQL, Full-stack, Web Applications, Technical Documentation, Documentation, Material UI, Single-page Applications (SPAs), Responsive Design, User Experience (UX), Responsive Web Apps, Deployment

Full-stack Developer

2016 - 2017
Smartiks
  • Built a real-time line chart page for the energy consumption of multiple devices.
  • Developed multiple charts to show overall consumption.
  • Fixed numerous bugs in the back end and front end and implemented several other features.
Technologies: Spring Boot, MongoDB, REST APIs, JavaScript, CSS, Front-end, HTML5, Front-end Development, Relational Databases, HTML, APIs, Agile, Full-stack, Web Applications, Documentation

Experience

Refactoring the Onboarding Flow for BEES Brazil Bank

I was part of the onboarding team of the BEES Brazil Bank, refactoring the entire flow together with three other engineers. We created a whole new microservice in Node.js to handle logic related to the onboarding.

The new microservice used the domain-driven design (DDD) to simplify communication between developers and people on the business side. It also provided better maintainability and more flexibility if a need to change a specific technology occurs in the future.

We used the outbox pattern to have transactional guarantees and reliable messaging that significantly reduced the possibility of data loss or corruption. We used CQRS to separate the writing from reading activity for more efficient scaling of storage capacity.

Merchant Checkout OTP Flow

I implemented a new mobile responsive OTP flow using atomic design methodology to quickly update components and enable more reusability for sharing designs within the team, allowing every designer to collaborate on the project. For better performance, we used Svelte so that the bundled file would be smaller.

When the user entered a valid email, an API call was made to check if it was linked to any users in the Skipify database. If so, an OTP modal would show, and a code would be sent to the user's phone. If not, the user would be redirected to a sign-up flow, and after that, an OTP would be sent.

After the OTP was verified, a new modal showed various information such as the shipping, address, order summary, and price.

ChefAssistant

https://docs.google.com/document/d/e/2PACX-1vSe4gIDPSxmTlAXWoGSNwf5QO6_Zv4q_Kz8gioKjUTlU6OYTfanfKNxs0c-QHExGAbbSCzRheV1z-3N/pub
A single-page web application that recommends recipes based on the ingredients and filters chosen by the user.

It contains authentication so users can save their favorite recipes and add undesired ones to the ignored list. The single-page web application was implemented using React, Node.js, and MongoDB.

Education

2015 - 2019

Bachelor's Degree in Computer Science

Federal University of Campina Grande - Campina Grande, Brazil

Skills

Libraries/APIs

React, Node.js, REST APIs, React Redux, Stripe, Stripe API, PayPal API, MobX, Highcharts, React Flow, Google API

Tools

Git, Jira, Webpack, Figma, Jenkins, GitHub, Sentry, Google Analytics, Google Optimize, Prisma, Xcode, Android Studio

Languages

TypeScript, ECMAScript (ES6), JavaScript, CSS, HTML, HTML5, Java, SQL, Python, GraphQL, TypeScript 3, PHP

Frameworks

Material UI, Express.js, Next.js, React Native, Spring Boot, Jest, Redux, Tailwind CSS, Angular, Svelte, NestJS

Paradigms

Best Practices, Agile, UX Design, Testing, Test-driven Development (TDD), CQRS, Microservices

Platforms

DigitalOcean, Amazon Web Services (AWS), Docker, New Relic, Azure, Vercel

Storage

Database Architecture, API Databases, MongoDB, PostgreSQL, MySQL, Relational Databases, Google Cloud, Redis

Other

Software Engineering, Web App Development, Web Development, Front-end, Front-end Development, APIs, Full-stack, Web Applications, CI/CD Pipelines, Technical Documentation, Documentation, Responsive Design, User Experience (UX), Responsive Web Apps, Pixel Perfect, Deployment, Full-stack Development, Mobile App Development, Styled-components, Springbot, ESLint, Atomic Design, eCommerce, Serverless, Single-page Applications (SPAs), Customer Relationship Management (CRM), PayPal, Algorithms, Domain-driven Design (DDD), TypeORM, Mobile UX, React Hooks, Content Management Systems (CMS), DocuSign, Digital Certificates, Charts, Responsive UI, Axios, Strapi, OpenAI, RESTFul APIs, Customer.io

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