Open for work opportunities & Eligible to work in the EU

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TypeScript & .NET Full-Stack Engineer

I work with technologies like .NET, Typescript, Next.js, React, Tailwind CSS, Docker, CI/CD to create automation projects, AI-powered tools and SaaS products

Guilherme de Castro

About me

I’m a Full Stack Software Engineer with a strong ownership mindset, experienced in building production-grade, scalable systems used in real business environments. I work primarily with TypeScript, Node.js, React, Next.js, and MySQL, and also have solid backend experience within the .NET ecosystem. I’ve owned features and systems end-to-end from requirements and architecture to implementation, CI/CD, deployments, monitoring, and long-term maintenance.

I’m driven by clean code, system design, and scalability, and I care deeply about delivering software that is reliable, observable, and built to last. I thrive in fast-paced, high-responsibility environments, working closely with product and business stakeholders to turn complex problems into simple, effective solutions. I’m now focused on expanding my career internationally while continuing to grow as an engineer.

Experience

Mid-Level Software Engineer (Full Stack & DevOps) at Aguia Diesel • Mar 2025 - Present

Part of an engineering team responsible for end-to-end delivery across the company software stack, including internal systems and the e-commerce platform. Own the full lifecycle: requirements alignment, architecture, implementation, deployments, monitoring, and ongoing maintenance covering frontend, backend, integrations, and infrastructure.

Key responsibilities

  • Build and maintain internal systems to support operational workflows and technician task management
  • Develop and evolve the e-commerce platform (features, performance, reliability)
  • Design and implement APIs, integrations, and database solutions
  • Manage CI/CD, deployments, monitoring, and incident resolution in a Linux environment
  • Collaborate on technical planning, estimations, and project execution

Tech stack

TypeScript, JavaScript, Next.js, React, Node.js, MySQL, Docker, Git, Linux, DevOps, Project Management, Frontend Development

Full-stack Developer (Part-time) at Sliftio • Jun 2025 - Present

Key responsibilities

  • Develop end-to-end features: UI/UX with Next.js (SSR/SSG/ISR) and REST APIs in .NET
  • Design and integrate relational databases (SQL Server/MySQL) using EF Core
  • Implement authentication and authorization (JWT/OpenID) following OWASP best practices
  • Write unit and integration tests, implement structured logging, and ensure observability
  • Automate build and deployment with Docker and CI/CD (GitHub Actions/Azure DevOps)
  • Monitor and optimize performance (Redis caching, profiling, APM)
  • Collaborate in code reviews, technical refinement, and product alignment

Skills

REST APIs, JavaScript, MySQL, Git, TypeScript, Next.js, DDD, Docker, DevOps, Linux, CI/CD, Selenium

Software Engineer (Part-time) at ITS MOB • Jan 2025 - Present

Contributing to software delivery with focus on REST API development and integrations using Python.

.NET Developer (Full-time) at Sliftio • Dec 2023 - Aug 2025

Key responsibilities

  • Develop end-to-end features with .NET (C#) and Web API, applying Clean Architecture and DDD when required
  • Design and integrate relational databases (SQL Server/MySQL) using EF Core with safe migrations
  • Write unit and integration tests, maintain structured logging (Serilog), and ensure observability (OpenTelemetry/APM)
  • Automate build and deployment with Docker and CI/CD (GitHub Actions)
  • Deploy on Linux (Ubuntu) with Docker/Compose, Nginx reverse proxy, HTTPS (Lets Encrypt), and systemd
  • Monitor and optimize performance (Redis caching, query profiling and tuning), and implement instrumentation metrics
  • Collaborate in code reviews, technical refinement, estimations, and alignment with product and business requirements
  • Integrate frontends (Next.js/React) via REST APIs and webhooks with reliable contracts

Skills

REST APIs, Docker, .NET, ASP.NET Core, DevOps, Entity Framework, SQL Server/MySQL, DDD, CI/CD, Docker, Nginx, Clean Code

Python Developer (Contract) at CP Marketing Digital and Podcast • Jul 2024 - Aug 2024

Development of social media automations using Python.

Skills: REST APIs, Microsoft SQL Server, Python

Software Programming Instructor (Part-time) at My Robot School - Brasil Franchising • Jan 2023 - Aug 2023

  • Taught C++ fundamentals (variables, control flow, functions, arrays, pointers, OOP) to beginner and intermediate students
  • Helped students develop problem-solving and debugging skills through hands-on exercises and small projects
  • Adapted explanations and examples to different learning speeds, making complex concepts easier to understand

Web Developer (Freelance) at Freelancer • Aug 2019 - Jun 2023

Skills: ASP.NET MVC, REST APIs, ASP.NET Core, Web Development, JavaScript, MySQL, C#, Node.js

Featured Projects

Skills & Tools

A creative problem solver with over 2 years of programming experience, I've explored diverse programming languages, libraries, and technology stacks, honing my skills in both Frontend, Backend, and DevOps/Infrastructure.

Eager to learn and adept at adopting new technologies, I thrive on expanding my skill set in the ever-evolving tech landscape.

Core Technologies

TypeScript
JavaScript (ES6+)
React
Next.js (SSR/SSG/ISR)
Node.js
C#

Backend

REST APIs
API Integrations
Authentication (JWT)
.NET
Prisma ORM

Databases

MySQL
SQL Server
Schema Design
Query Optimization

DevOps & Infrastructure

Git
CI/CD (GitHub Actions)
CI/CD (Azure DevOps)
Docker
Linux
Nginx
Monitoring
Incident Support

Engineering Practices

Clean Code
Modular Design
API Contracts
Debugging
Refactoring (Production Systems)