Frontend for real products.Care in every interaction.
I’m Giovanni Fernandes Vicentin, a software engineer focused on web frontend. I build interfaces with React, Next.js, and TypeScript at Itaú Unibanco, with experience at Carrefour and Sam’s Club Brazil. My backend experience helps me connect those interfaces to the services behind them.
Brazil / Software for the webReact / Next.js / Node.js
01 / Experience
Engineering in production.
I work across interfaces and backend systems in product teams. Here are some of my contributions to production applications.
Itaú Unibanco
Software Engineer
2026 — Present
A new web foundation for the Itaú app.
How I replaced native repositories with a high-performance web foundation and structured the frontend for the 2027 relaunch.
Itaú HubApp Modernization
I replaced the navigation hub’s native architecture with a single web project built with React and Next.js, drastically accelerating app deployments and rollouts.
+24%Loading Performance
I implemented a local caching strategy to minimize backend calls, speed up loading across app journeys, and deliver smoother navigation.
New AppApp Relaunch Planned for 2027
Development of the app’s new visual identity. I built a modern interface designed from the outset to support AI integrations and enhance the user experience.
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I built the web foundation of the Itaú app’s navigation hub from scratch, replacing two native repositories with a single project in React and Next.js. The architecture combines WebView, static site generation (SSG), and BFF integration, enabling greater release autonomy and faster feature delivery.
I implemented local caching to reduce backend requests and improve loading times across app journeys, achieving a gain of 24% in loading performance. I also contribute to an entirely new app interface, with a relaunch planned for early 2027.
Alongside my work on the app, I was the first Itaú employee to use and validate an internal tool for specification-driven development with AI agents, skills, and MCP. This work helped assess the tool’s use in the bank’s development workflow.
ReactNext.jsNode.jsGoTypeScriptAIWebViewSDDMCP
Carrefour & Sam’s Club
Software Engineer
2024 — 2026
Scale and Revenue at Sam’s Club
Fullstack architecture and performance optimization to support more than 1 million new members and improve membership conversion.
1.4M+ MembersAcquisition at Scale
I built the registration flow end to end, from the frontend to the BFF and backend. The architecture supported more than 1.4 million new members joining in 2024 and 2025.
+26% ProfitMembership Plus Launch
I implemented the fullstack core of the club’s new membership tier, including acquisition, upgrade, and downgrade flows. This work contributed to a 26% increase in profit from membership fees.
+40% CWAOptimized Core Web Vitals
I led the migration of the styling layer from styled-components to Sass. The change cut loading time by 1.8 seconds and increased the PageSpeed Insights score by 40%.
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I built the Sam’s Club member registration flow end to end, developing the frontend, BFF, and backend integrations that supported more than 1.4 million new users in 2024 and 2025. I also implemented Membership Plus, including interfaces and endpoints for purchases, upgrades, and downgrades, contributing to a 26% increase in profit from membership fees.
I connected architectural improvements to performance and conversion gains across the shopping experience. I migrated the styling layer from Styled-components to Sass, cutting load time by 1.8 seconds and increasing the Google PageSpeed Insights score by 40%. I also built an embedded checkout integrated with external payment gateways, eliminating redirects and contributing to a 20% increase in purchase completion rate.
I improved visibility into the customer journey through advanced Google Analytics tracking. Identifying bottlenecks guided improvements that helped reduce complaints by 10% and increase engagement by 15%. I also built a scalable API to manage account and payment data for more than 500,000 users, enabling new promotional campaigns and retention initiatives.
Digital transformation of critical processes: from RPA to high-performance integrations that scale operations without increasing headcount.
80K+Tax documents delivered
I improved the integration architecture, replacing RPA workflows with high-performance APIs. The solution processed 10 documents per second and enabled the delivery of more than 80,000 tax payment documents.
+30%Profit margin
I automated critical payroll and labor administration processes, enabling the team to serve new clients without increasing headcount. The efficiency gains contributed to a 30% increase in the department’s profit margin.
90%+Code coverage
I implemented unit and automated test suites for the core tax document delivery system, achieving more than 90% code coverage. This foundation strengthened the reliability of critical deliveries and confidence in future system changes.
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I modernized tax document processing and delivery by replacing RPA workflows with API integrations. The new architecture processed 10 documents per second and enabled the delivery of more than 80,000 tax payment documents, using Base64 to encode the files. I also built an internal tax management portal with JWT authentication and digital certificates, integrated with government services to automate data retrieval and PDF downloads.
In the payroll and labor administration department, I automated operational processes that enabled the client portfolio to grow without increasing headcount, contributing to a 30% increase in the department’s profit margin. This work connected technical improvements to the business’s capacity to expand.
I strengthened the reliability of critical deliveries with unit and automated test suites for the core tax document delivery system, achieving more than 90% code coverage. I also mentored a junior developer from onboarding to technical autonomy in delivering complex RPA and API solutions, expanding the team’s delivery capacity.
ReactNode.jsNestJSPythonAPIsRPA
02 / Projects
Ideas turned into tools.
Projects created to solve real-world challenges in engineering, accessibility, and well-being. End-to-end products with open-source code, ready for you to test and explore the architecture.
01
Big O Analyzer
Understand how an algorithm’s cost grows with its input.
Heuristic static analysis of JavaScript, Python, and Java using abstract syntax trees (ASTs) and control flow.
Organize matches and tournaments for EA FC 26 and FC 25. Team draws with category and star-rating filters, balanced matchups, and tournament brackets.
Megazord
Explore STEAM concepts through hands-on learning. I brought games and activities together in an accessible educational platform.
Frank Metálicas
Give a company a presence on the web. I built the Frank Metálicas website with a focus on digital presence and search engine optimization.
03 / About
Attention to experience. Technology with purpose.
Giovanni Fernandes Vicentin
I believe good software should, above all, make everyday life easier and improve people’s quality of life.
I work at the intersection of human impact and engineering. I develop modern interfaces with a deep focus on how customers navigate, understand, and feel when using a product.
To support this vision, I also work on backend development and infrastructure. Understanding data flows and ensuring high performance are my tools for making technology work for people.
Accessibility (a11y) · Web Vitals/Performance · SDD · MCP · AI Agents
04 / Contact
Next steps.
Whether you want to discuss architecture decisions, accessibility, or the future of your product, my inbox is open to good connections. Feel free to send a "hello".
