João Guedes

Professional Summary

Versatile Software Developer with strong experience in Go and Unix-like systems (Linux, BSDs). Skilled in Microservices, distributed systems architecture, message-driven architectures (gRPC, Kafka, Asynq), API integrations, OCR systems, deployment pipelines, and automation tooling. Experienced in and shell scripting (bash, ksh, zsh) for system utilities, server management, and desktop automation. Experienced in performance optimization strategies including connection pooling, caching, and concurrent programming. Practical knowledge in Data Science & AI with applied projects in OCR and LLMs. Strong background in container technologies (Docker, FreeBSD jails) and filesystem administration (ZFS, ext4, XFS).

Technical Skills

• Languages: Go (primary), Python (Data microservices), Elixir (Lightweight broadcasting), ClojureScript (primary for UI), C, Shell Scripting (bash, ksh, zsh), Node.js, Haskell
• Frameworks/Library: Gin, Gorilla, Reagent, FastAPI, Flask, LangChain, Pandas, OpenCV, Vue.js
• Distributed Systems & Messaging: Microservices Architecture, gRPC, Protocol Buffers, Apache Kafka, Asynq, REST APIs, Messagering, High-scale Websocket communication strategies.
• Systems & Infrastructure: Linux (Ubuntu, Debian, CentOS, etc), BSD (FreeBSD, OpenBSD), Docker, Podman, FreeBSD jails, OpenSSH, OpenSMTPD, ZFS, ext4, XFS, SSH administration
• Performance & Optimization: Connection pooling, Query optimization, Redis caching, Asynq job scheduling, Concurrent programming, Load balancing, Application profiling
• Databases: PostgreSQL, MySQL, MongoDB
• AI & Data: OCR (Mistral-OCR, OpenCV, pyzbar), Statistical analysis
• DevOps: CI/CD pipelines, Deployment automation, Infrastructure as Code, Build systems
• Philosophy: KISS principles, UNIX, Open-source, Libre

Professional Experience

Backend Engineer | AxxisPay, Brazil | Jan 2023 – Present (2 years)

• Developed production-grade Go backend modules and automation tooling for financial technology platform.
• Implemented MinIO object storage integration using S3-compatible API for scalable file and document management.
• Built Python microservice for restricted product recognition achieving 99.6% accuracy across 5,646 real-world cases using computer vision techniques.
• Developed invoice reader system supporting multiple Brazilian fiscal document formats (NFC-e, NF-e, CF-e-SAT) using QR code/barcode scanning integrated with OCR (Mistral + OpenCV).
• Implemented Go-based web scraper for Brazilian NFC-e fiscal nvoices with direct integration to Secretaria da Fazenda systems.
• Architected flexible search routes with dynamic SQL query building in Go for complex filtering and data retrieval.
• Integrated WPS parking API enabling real-time payment processing with OCR capabilities in Go.
• Integrated ingresso.com API for movie listing, scheduling, and ticket purchasing functionality in Go.
• Implemented indirect automatic PIX payment processing in banking application backend.
• Integrated indirect automatic PIX API in Go for seamless payment flows.
• Maintained and enhanced Node.js frontend applications.
• Containerized services using Docker and deployed to Railway platform with optimized database schemas and performance tuning.

System & Automation Projects | Personal / Open Source | 2021 – Present

• Developed monitoring system for ZFS filesystems using gRPC. Implemented server-side logic in Elixir with cross-language RPC communication capabilities.
• Built a simple streaming application in Go for peer-to-peer media streaming with concurrent download management and subtitles option with subliminal.
• Created a demonstration of an authentication service in Go implementing JWT-based security, password hashing, and HTTP-only session management using Gin framework.
• Maintained comprehensive repository of reusable code snippets and automation tools across multiple languages (Shell, Python, Go, C, Clojure).
• Developed Go interop library for executing Python sentences.
• C utilities and Ports for OpenBSD.
• Shell scripts for automation (GIF wallpapers, system monitors).
• Developed a Haskell program to manage and regenerate my static article website.

Data Science & AI Projects | University / Personal | 2024 – Present

• Coursework: NoSQL chatbot (Flask + PyMongo) with UI in ClojureScript.
• Coursework: Developed a Go API and a Python API focused in agentic tasks
• Developed statistical analysis tools and data processing pipelines.

Education

Bachelor of Data Science & AI | PUC-Campinas | 2024 – Present

Additional Interests

• UNIX systems, privacy & open-source advocate (since 15 y/o).
• Aspiring contributor to BSDs projects and open-source community.
• Experimenting with Functional programming paradigms and languages.
• Strong advocate of UNIX philosophy and sustainable development practices.
• Continuous learner staying current with emerging technologies while maintaining deep expertise in foundational system administration concepts and Unix philosophy.
• Maintains technical blog at fugu.cafe.