João Paulo
Ferrete

Tools I reach for.

Things I've built.

Go Lister

Live

A real-time collaborative music platform: one room, one link, and a queue everyone controls playing in sync. Kotlin/Spring Boot backend, three React frontends, and a Chromecast receiver.

KotlinSpring BootWebSocketRedisReact

The engineering

The problem

Keeping several devices on the same second of the same song, when each provider exposes playback differently — and the browser won't let you authenticate a WebSocket properly.

The decision

The server owns the queue and the clock. The WebSocket is authenticated by ticket instead.

The consequence

nginx became the only ingress to the backend, with TLS terminated at Cloudflare.

Terminal Assistant

Notes, tasks and smart home under a single trigger engine, in one command. Automations are plain Python: your machine's own state drives your lights and your reminders.

PythonCLIHome AssistantSQLiteAutomation

The engineering

The problem

Home Assistant does not know you just joined a call, and GNOME does not know how to turn on a lamp.

The decision

Its own trigger engine in Python, and one hard rule: no integration may be mandatory.

The consequence

The core runs anywhere Python runs and a file can be written.

lifter → Go Lifter

Closed beta PyPI

Two projects, one lineage: lifter, a training coach shipped as a Python CLI on PyPI, and Go Lifter, the native Android app in Kotlin and Compose that succeeds it — now in closed beta on Google Play.

PythonKotlinComposePyPIGoogle Fit

The engineering

The problem

A coach is only useful if it remembers your history — and the minute it remembers, it can also ruin your data.

The decision

The coach proposes, it never writes: every change goes through your approval.

The consequence

The CLI shipped to PyPI with six interchangeable model providers and independent profiles.

Also built

• Lighter A GNOME extension that improves video-call lighting with adjustable white screen borders. JavaScript · GJS
• Container Loading Problem Scientific-initiation research in combinatorial optimization: heuristics for a high-complexity packing problem. C++
• MarathonAlg A curated library of algorithms and data structures for competitive programming contests. C++

Where I've been.

1. Feb 2025 — Present

   Software Engineer II & Tech Lead — IoT Video

   Cobli · São Mateus (Remote)

   Tech Lead of the Camera/IoT Video squad: Architected real-time services for low-latency communication between embedded hardware and backend. Built scalable microservices in Kotlin, Java/Spring Boot, Go, and Python. Led stream processing with Apache Flink. Acted as the technical focal point for international vendors on firmware and hardware homologation.

2. Jan 2024 — Jan 2025

   Software Engineer I

   Cobli · São Mateus (Remote)

   Built and maintained critical microservices for IoT Video in a polyglot environment. Engineered data pipelines with Apache Flink and Scala, ensured high availability for video-ingestion infrastructure, and accelerated internal workflows by developing admin tools with React.

3. Aug 2022 — Dec 2023

   Software Engineering & Embedded Systems Intern

   Cobli · São Mateus (Remote)

   Helped create the Video Telemetry product from the ground up — backend (Kotlin, Java, Python, Go, Scala) and frontend (React, TypeScript) — plus R&D for embedded systems and microservices setup.

4. Mar 2022 — Oct 2022

   Development Manager / Associate

   Adapti Soluções Web · Junior Enterprise

   Led a development squad and built fullstack web systems for clients with PHP (Laravel), HTML, CSS, and JavaScript.

5. 2018 — Exp. Mar 2026

   BSc in Computer Science

   UFES — Federal University of Espírito Santo

   Teaching assistant (Data Structures, Functional Programming) · scientific initiation in combinatorial optimization · competitive programming (SBC) · Vice-General Chair of VI ENCOMP.