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Guilherme Focassio

@guilhermefocassio

Full-stack JavaScript engineer at OnSign who improved media delivery efficiency about 10× with a Node.js and TypeScript API.

Brazil

Message

At OnSign, I designed and implemented a high-throughput Node.js and TypeScript file delivery API with LRU caching, improving media delivery efficiency about 10×.

I also built an on-device AI monitoring system that runs vision models on signage hardware, and contributed REST APIs and a local HTTP service for client–device communication.

At OnSign, I led a production migration from localStorage to IndexedDB and diagnosed memory leaks and performance regressions. I delivered production fixes and features across five client platforms.

As an independent full-stack engineer, I build and ship client applications with Next.js, React, TypeScript, and Supabase. I also built the frontend and Django REST API for a statistical analysis platform.

Experience

Work history, roles, and key accomplishments

Current

Software Engineer

Current

OnSign

May 2024 - Present (2 years 5 months)

Designed and implemented a high-throughput file delivery API in Node.js/TypeScript with an LRU caching layer, improving media delivery efficiency ~10x. Built and deployed an on-device AI monitoring system for digital signage hardware, and led a client-side storage migration to IndexedDB.

TypeScript NodeJS WebAssembly CEF WebOS Tizen BrightSign IndexedDB LRU Caching REST APIs

Current

Independent Full-Stack Engineer

Current

Client WebApplications

Jan 2024 - Present (2 years 9 months)

Built and shipped responsive frontends in Next.js/React, TypeScript, and TailwindCSS. Delivered full-stack web applications end-to-end, including requirements, data modeling, implementation, deployment, and maintenance.

Next.js React Supabase PostgreSQL Tailwind CI CD Vercel GitHub Actions

Software Engineer, Intern

OnSign

May 2023 - May 2024 (1 year)

Worked on production fixes and features across five client platforms, diagnosed memory leaks, and implemented logger rate limiting and playback lifecycle optimizations.

TypeScript NodeJS WebAssembly CEF WebOS Tizen BrightSign IndexedDB LRU Caching REST APIs

Education

Degrees, certifications, and relevant coursework

Federal University of Santa Catarina

Bachelor of Science, Systems Engineering

Pursuing a B.S. in Systems Engineering with expected graduation in January 2027. Coursework includes Data Structures & Algorithms, Distributed Systems, Operating Systems, Computer Networks, and Software Engineering.