Willer is available for hire
Hire WillerWiller Rodrigo Silva
Verified Expert in Engineering
Front-end Developer
São Sebastião da Bela Vista - Minas Gerais, Brazil
Toptal member since July 23, 2026
Bio
Willer has spent 7 years building mobile and web solutions across fintech, eCommerce, and government platforms. His toolkit centers on React, TypeScript, and Expo. While at B2ML Sistemas, Willer led the development of a driver app from scratch and supervised 2 front-end developers.
Portfolio
Zagalabs
TypeScript, React, GraphQL, Problem Solving, Clean Code, Front-end Development...
B2ML Sistemas
React Native, TypeScript, Zustand, Firebase, Expo, React Native Testing Library...
BANKEI Oficial
React Native, Expo, TypeScript, CI/CD Pipelines, Problem Solving, Clean Code...
Experience
- React Native - 7 years
- React - 7 years
- JavaScript - 6 years
- Problem Solving - 6 years
- TypeScript - 5 years
- Clean Code - 5 years
- Expo - 4 years
- CI/CD Pipelines - 4 years
Preferred Environment
Jira, Git, Slack, Notion, Cursor AI, Gmail, Claude, TypeScript, React, OS X
The most amazing...
...app I've built is a language learning platform that led to 90% of users switching from web to mobile for their activities.
Work Experience
Front-end Engineer
2025 - PRESENT
Zagalabs
- Built and shipped many features across a mobile app, web app, and admin dashboard serving Chief's executive-women membership platform, including search, forms, and referral flows.
- Developed dozens of reusable UI components for a shared design system used across three products, eliminating duplicate styling work between web and mobile teams.
- Implemented paginated search across member and event listings, improving performance and usability for lists containing thousands of records.
Technologies: TypeScript, React, GraphQL, Problem Solving, Clean Code, Front-end Development, Mobile Development, Cross-platform App Development, ChatGPT, Front-end, User Interface (UI), User Experience (UX), Mobile App Development, Claude Code, Front-end Architecture
Front-end Developer
2021 - 2026
B2ML Sistemas
- Developed a government medication management platform featuring complex forms, intricate UX design, and sophisticated data flow. Streamlined data flow and ensured accuracy, enhancing usability and compliance.
- Designed intuitive interfaces and implemented robust validation for intricate data structures.
- Oversaw app architecture as a mobile tech leader, led feature development, and ensured code quality.
- Supervised 2 front-end developers, managed project timelines, mentored the team, optimized performance, facilitated cross-team collaboration, and aligned development with strategic goals.
- Led the development of a driver app from scratch, creating a design system and applying best practices.
- Developed core features such as real-time navigation, route optimization, and vehicle tracking, ensuring a seamless and efficient UX.
- Led the development of a bill manager app featuring bill tracking, reminders, and integration with banks and credit cards.
- Designed intuitive interfaces for the bill manager app, integrated payment gateways, and optimized performance.
- Ensured secure data management for the bill manager app and enhanced UX with smooth navigation and personalization.
- Participated in the development of an HR app for recruitment and selection, enhancing UX through intuitive interfaces and streamlined workflows.
Technologies: React Native, TypeScript, Zustand, Firebase, Expo, React Native Testing Library, Jest, React Hook Form, Sentry, Zod, React Query, Problem Solving, Clean Code, React, Multi-tenant Architecture, Node.js, Front-end Development, Mobile Development, Cross-platform App Development, ChatGPT, Front-end, User Interface (UI), User Experience (UX), Mobile App Development, Claude Code, Front-end Architecture
Senior Mobile Developer
2024 - 2025
BANKEI Oficial
- Developed a banking app for the cryptocurrency market.
- Defined the app architecture using a feature-sliced design.
- Implemented the design system and set up error monitoring.
- Configured CI/CD pipelines to ensure continuous and secure deliveries.
- Implemented robust strategies to provide a reliable and intuitive flow with security and user experience as top priorities.
Technologies: React Native, Expo, TypeScript, CI/CD Pipelines, Problem Solving, Clean Code, React, Mobile Development, Fintech, Cross-platform App Development, Front-end, User Interface (UI), User Experience (UX), Mobile App Development, Front-end Architecture
Senior Mobile Developer
2022 - 2024
Platform Builders
- Developed an eCommerce app for hypermarket appliance sales.
- Optimized user interfaces to enhance UX and functionality for the eCommerce app.
- Ensured smooth integration with back-end systems for the eCommerce app.
- Provided a seamless experience for the sales team, resulting in increased sales.
Technologies: React Native, TypeScript, Styled-components, MobX, Native Modules, CI/CD Pipelines, Problem Solving, Clean Code, React, Mobile Development, Cross-platform App Development, GitHub Actions, Bitbucket, Front-end, User Interface (UI), User Experience (UX), Mobile App Development, Front-end Architecture
Senior Mobile Developer
2021 - 2022
Companhia Brasileira De Servicos De Marketing S/A
- Worked on developing the Dotz super app, a benefits platform, utilizing micro front-end architecture concepts.
- Collaborated with the growth marketing team to manage and optimize campaigns.
- Implemented and managed campaign optimization tools within the Dotz app, directly supporting growth initiatives and improving engagement across the platform's 50+ million user base.
Technologies: React Native, TypeScript, Redux, Jest, Sentry, Bitrise, Problem Solving, Clean Code, React, Mobile Development, Fintech, Cross-platform App Development, Bitbucket, Front-end, User Interface (UI), User Experience (UX), Mobile App Development, Front-end Architecture
Front-end Developer
2019 - 2021
B2ML Sistemas
- Built and maintained a Brazilian government web application using React and related technologies, ensuring seamless integration with back-end systems.
- Developed a language learning app from scratch using React Native, leading to 90% of users switching from the web app to the mobile app for activities. Incorporated features like quizzes, vocabulary exercises, and progress tracking.
- Developed and integrated cosmetics eCommerce functionalities, including product listings, payment processing, and user account management.
Technologies: React Native, Redux, Sass, Webpack, TypeScript, Material UI, Problem Solving, Clean Code, React, Multi-tenant Architecture, Node.js, Front-end Development, Mobile Development, Cross-platform App Development, Front-end, User Interface (UI), User Experience (UX), Mobile App Development, Claude Code, Front-end Architecture
Software Developer Intern
2017 - 2019
Instituto Nacional de Telecomunicações - Inatel
- Worked as a tester and software developer at the Inatel Competence Center (Qualcomm Lab).
- Implemented several types of tests, such as unit tests, integration tests, functional tests, load tests, performance tests, battery tests, and safety tests.
- Developed software using languages such as Java, C#, JavaScript, and Python.
Technologies: Java, C#, JavaScript, Python, Problem Solving, Clean Code, Front-end, User Interface (UI), User Experience (UX), Mobile App Development
Experience
Chief
https://chief.com/A membership platform. I worked as a cross-platform engineer, shipping features across all products. I also helped build out our shared UI component library so different teams could ship consistent designs without duplicating work. This involved close collaboration with Product, Design, and back-end engineers to turn specifications into working features across the stack.
Education
2016 - 2020
Bachelor's Degree in Computer Engineering
Instituto Nacional de Telecomunicações - Inatel - Brazil
Skills
Libraries/APIs
React, React Hook Form, React Query, React Native Testing Library, Zod, MobX, SendBird, Node.js
Tools
Expo, Git, Jira, Sentry, Bitbucket, ChatGPT, Slack, Notion, Webpack, GitLab CI/CD, Figma, CircleCI, Nx, Braze, Claude, Claude Code
Languages
TypeScript, JavaScript, GraphQL, Sass, Java, C#, Python
Frameworks
React Native, Jest, Redux, Material UI, Detox
Paradigms
Clean Code, Design Patterns, Mobile Development, Software Testing
Platforms
Android, iOS, Visual Studio Code (VS Code), MacOS, Firebase, Bitrise, Sanity Studio, Maestro, OS X
Storage
Datadog
Other
Code Review, Problem Solving, Front-end Development, Cross-platform App Development, Front-end, User Interface (UI), User Experience (UX), Mobile App Development, Front-end Architecture, Gmail, Styled-components, Multi-tenant Architecture, Fintech, GitHub Actions, Cursor AI, Software Development, Zustand, CI/CD Pipelines, Native Modules, Storybook, System Design, Chakra UI
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