Frontend Developer • Angular • React

Hermino Júnior

Minimal, accessible interfaces with a product mindset.

I design and build responsive web experiences with a focus on clarity, performance, and refined UI details. This portfolio highlights selected work, skills, and the approach I bring to modern frontend teams.

View projects
6+ yearsFrontend experience
8+ productsDelivered for clients
Design-firstAccessible systems

About

About me

Frontend Developer with 5+ years of experience building modern, responsive web applications. Specialized in React.js, TypeScript, and Angular, with a strong foundation in UI/UX principles. Passionate about creating accessible, performant interfaces using the latest web technologies and best practices. Experienced in state management, component architecture, and responsive design.

Work

Featured projects

TOTVS S.A1 project

LYNN

Senior Frontend Developer on LYNN, TOTVS’s B2B AI foundation for building, orchestrating, and governing AI agents, a strategic, high-visibility initiative for the company and the Brazilian market. Responsible for developing scalable, maintainable interfaces with Angular and TypeScript, applying modern practices such as Signals, standalone components, and OnPush change detection within an enterprise monorepo. Ensures code quality and reliability through unit testing with Vitest and contributes to frontend architecture and reusable component development.

AnglarTypeScriptJavaScript (ES6+)UI/UX DesignResponsive Design
Confidential — cannot be disclosed due to contractual obligations

INDT2 projects

ITN5 projects

Experience

Professional highlights

TOTVS S.A

08/2025 - Present

Senior Frontend Developer

Senior Frontend Developer at LYNN, a strategic initiative by TOTVS focused on creating AI agents—a high-visibility, high-impact project closely monitored by the market. I am responsible for developing scalable, maintainable interfaces using Angular and TypeScript, applying modern practices such as Signals, standalone components, and OnPush change detection within an enterprise monorepo. I ensure code quality and reliability through unit testing with Vitest, while also contributing to frontend architecture decisions, the development of reusable components, and AI-assisted engineering workflows.

Frontend development for LYNN, a TOTVS platform for creating AI agents—a strategic, high-visibility product.
Building scalable, high-performance interfaces using Angular (Signals, standalone components, OnPush) and TypeScript within an enterprise monorepo.
Creating and maintaining unit tests with Vitest, ensuring high quality and reliability for critical features.
Contributing to frontend architecture, developing reusable components, and defining code quality standards for the entire team.
Applying prompt engineering and AI agents to optimize development workflows, such as component migration.
AngularTypeScriptJavaScript (ES6+)UI/UX DesignResponsive Design

INDT - Institute for Technological Development

02/2022 – 08/2025

I joined the company as a junior frontend developer and quickly established myself as the lead frontend developer for web platforms. When demand arose for a new web application, I took ownership of the entire frontend architecture using React and TypeScript. I designed and implemented responsive, accessible interfaces with modern UI/UX best practices. After 8 months, I received a promotion due to high quality deliveries and exceptional frontend expertise.

Lead frontend developer on collaborative project with Motorola.
Built responsive, accessible interfaces using React and TypeScript.
Developed web application UI/UX for natural language processing tools.
Expertise in modern frontend architecture, state management, and UI/UX design.
ReactTypeScriptJavaScriptHTML5CSS3UI/UX DesignResponsive DesignAccessibility

Northern Institute of Technology and Business - ITN

08/2020 - 02/2022

Junior Systems Development Analyst

I worked as frontend developer on 5 projects, all using Angular 8+ with Material Design. I took ownership of the entire frontend architecture and UI/UX implementation. Despite working with legacy codebases and limited documentation, I successfully delivered modern, responsive interfaces with excellent user experience. Daily collaboration with clients helped shape intuitive designs that met business requirements.

Built responsive frontend interfaces for computer vision applications.
Led frontend development on 6 projects using Angular and Material Design.
AngularTypeScriptJavaScriptMaterial DesignHTML5CSS3Responsive DesignUI/UX

Federal University of Roraima - UFRR

10/2018 - 04/2019

Network Assistent

Supported the network department by diagnosing and resolving customer connectivity issues via phone, ensuring fast service restoration and customer satisfaction.

Handled inbound support calls, diagnosing and resolving customer internet connectivity issues.
Guided customers through troubleshooting steps such as router configuration, cable checks, and network resets.
Escalated complex cases to the network team with clear technical reports, reducing resolution time.
DockerPrometheusGrafana

© 2026 Hermino Barbosa de Freitas Júnior