João Küster
Senior Frontend Engineer
Based in Brazil · Open to Remote
About
Results-driven engineer focused on building scalable, high-performance web applications that ship fast and last long.
With over six years of experience in frontend engineering, I specialize in TypeScript, React, and Node.js. I've shipped 10+ products across B2B and SaaS platforms, with deep expertise in telecom and retail systems.
Currently leading frontend architecture at Eleven Soft, building apps that serve 50,000+ active users with real-time communication.
When I'm not coding, you'll find me on the soccer field, dueling in Yu-Gi-Oh! GX on PSP, or spending quality time with family and friends.
Skills
Experience
Eleven Soft
Senior Frontend Engineer
- Led frontend architecture for apps serving 50,000+ active users
- Real-time communication with WebSockets — 40% latency reduction
- Implemented Sentry & DataDog monitoring — 35% fewer incidents
- Mentored 4 frontend developers, drove TypeScript adoption (25% fewer runtime errors)
MYRP Gestão Empresarial
Frontend Engineer
- Migrated Webpack → Vite — 55% faster build times
- Built shared design system: 40+ components across 8 applications
- Led JavaScript → TypeScript migration — 30% bug reduction
- 98% cross-browser compatibility achievement
SaperX
Frontend Developer
- Shipped 12+ Vue.js releases for enterprise clients
- Raised test coverage from 45% to 85% with Jest & Cypress
- 40% load time improvement via code splitting & lazy loading
KeBooK
Junior Frontend Developer
- Built mobile-first responsive interfaces with React & CSS-in-JS
- Developed reusable component library — 20% faster feature delivery
- Collaborated on RESTful API design and Agile ceremonies
Projects
ESH — Server Access Management
Centralized server access platform with session recording and audit trails, targeting mid-market enterprise clients. Built for security-first infrastructure management.
RDP Web Integration
Full-stack browser-based RDP solution — React frontend, Laravel API, and Apache Guacamole connecting to Windows Server 2022 instances on AWS EC2.
Component Library & Design System
Led the design system initiative — 40+ components documented in Storybook, adopted across 8 applications by multiple engineering teams.
Education & Languages
Let's Build Something Together
I'm always open to new opportunities, interesting projects, and good conversations. Whether you need a frontend engineer or just want to say hello — reach out.