I’m a .NET developer with hands-on experience building complete solutions as a freelancer: APIs, backend systems, external service integrations, and performance optimization. I enjoy working autonomously, understanding real-world problems, and delivering functional, maintainable software.

I’m particularly interested in building efficient, scalable systems with a strong focus on performance and code quality.

I’m currently looking for a stable position where I can contribute from day one and continue growing into a mid-level role.

Languages:
C#, SQL, JavaScript

Frameworks & Libraries:
ASP.NET Core · .NET Framework · .NET 8/10 · Entity Framework Core · Dapper

Databases:
SQL Server · PostgreSQL · SQLite

Tools:
Git · Docker/Podman · Postman · Azure DevOps (basic)

Methodologies:
SOLID · Clean Code · REST APIs · Basic testing · Basic CI/CD

Technologies: ASP.NET Core, EF Core, SQL Server, Docker

• Designed and implemented a REST API integrating an internal system with an external provider, handling authentication and data synchronization.
• JWT authentication, data validation, and robust error handling.
• Optimized queries, reducing response times by ~40%.
• Deployed using Docker containers.

Technologies: .NET 7, PostgreSQL, Dapper

• Developed the full backend for an internal management application.
• Implemented CRUD operations, pagination, filtering, user roles, and business logic.
• Performed manual testing and implemented basic automated tests using xUnit.

Technologies: .NET Worker Services, Quartz.NET

• Implemented a scheduled task system for sending notifications.
• Integrated with external APIs and structured logging.
• Error handling and retry mechanisms.

I contribute to open-source projects on GitHub, including bug fixes, enhancements, and code improvements.

Through this, I’ve gained experience working with established codebases, participating in code reviews, and collaborating in distributed teams.

Currently most active on Stride Game Engine, and recently contributing to .NET Community Toolkit.

While my main professional focus is backend development, I also have hands-on experience in:

• Graphics programming (DirectX, HLSL shaders)
• Game development concepts and architectures
• Performance optimization at low-level and system level

These areas have strengthened my understanding of performance, memory management, and efficient system design.

• Strong autonomy and ability to solve real-world problems.
• Experience delivering end-to-end projects, from design to deployment.
• Ability to quickly adapt to new environments and technologies.
• Continuous improvement mindset and focus on best practices.

LinkedIn: Mario Guerra
Email: mario.guerra.dev@outlook.com
GitHub: This profile 😊