Mihael Costa/about
Senior .NET Engineer · Backend & Cloud · AI-Augmented

Backend systems that have to be right in production — and, lately, the agents that help build them.

Five years of production .NET: service decomposition, event-driven integrations, and the SQL that has to survive Black Friday traffic on a franchise network. Currently at Linx, one of Brazil's largest retail-tech platforms, owning backend modules on an Azure-native microservices stack.

The newer habit is AI-augmented engineering — designing GitHub Copilot Agents and reusable Skills that take the repetitive, error-prone parts of the job off a team’s plate. This site runs on the same instinct: nothing here is a claim you have to take on trust when you could instead run it.

Stack

click a tag to check it against the work above

Languages

Frameworks & runtime

Cloud & messaging

Databases

Architecture

Testing & quality

Frontend

AI tooling

click a tag — the dot means it shows up in at least one project below

Experience

  1. .NET Engineer· LinxAug 2025 – Present

    São Paulo, Brazil · One of Brazil's largest retail-tech companies — food service & retail platform

    • Owns backend modules in a microservices architecture at enterprise scale, serving large franchise networks on C#, .NET 8/9/10 and Azure DevOps CI/CD.
    • Architected an asynchronous event-driven messaging pipeline on Azure Service Bus, improving decoupling and resilience for third-party integrations.
    • Drives container orchestration on Azure Kubernetes Service and Argo Workflows for reliable, automated rollouts.
    • Introduced GitHub Copilot Agents and reusable Skills for refactoring, module generation and bug resolution.
    • Brought in Stryker mutation testing alongside xUnit, SonarQube and coverage reporting.
    • Set up observability on Azure Monitor and Application Insights for proactive incident detection.
  2. .NET Developer· Sys3 SystemsSep 2024 – Jul 2025

    Bauru, Brazil · Outsourced, embedded on the Linx food service & retail platform

    • Migrated .NET Framework modules to .NET 6/8, refactoring legacy code while fully preserving business logic and contracts.
    • Implemented CQRS to improve architecture, scalability and separation of concerns.
    • Optimized critical SQL stored procedures — 60%+ improvement on high-volume operations.
  3. .NET Developer· MoovefyJan 2021 – Aug 2024

    Bauru, Brazil · SaaS for car rental and truck fleet management — team of 4–6

    • Built a BI reporting module from scratch — dynamic dashboards and data visualizations for operational insight.
    • Designed a full contract-signing flow end to end: lead acquisition, generation, digital signing, post-sales.
    • Built an in-app image editor and real-time Kanban boards for workflow management.
    • Cut operational steps by 40% with a POS implementation; sped up queries by moving to Dapper.
    • Containerized the stack with Docker across systems handling millions of monthly requests.

Outside the stack

  • Espresso, at the grind size that took three weekends to dial in.
  • Chess by correspondence, played badly against people who actually study it.
  • A home lab that started as "just a Pi for Pi-hole" and is now a k3s cluster nobody asked for.
  • Long, slow runs with a podcast queue that outpaces the mileage.