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Johan Herreño

@johanherreo

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Software Developer | .NET · C# · ASP.NET Core · SQL Server | Backend

Colombia

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Software Developer with 5 years of professional experience in C#, specialized in building interactive applications and the backend behind them.

Hands-on experience building and maintaining REST APIs with ASP.NET Core, SQL Server, and MongoDB, as well as backend services using Node.js, Firebase, and Supabase. Strong foundation in SOLID principles, clean architecture, and CI/CD, with a track record of delivering production software in healthcare and education.

Experience

Work history, roles, and key accomplishments

Interactive Software Developer

Alternova

Jun 2024 - Jan 2026 (1 year 7 months)

Delivered production healthcare software (HIPAA, OWASP). Built REST APIs and backend services with Express.js and Firebase for auth, user data, and dynamic content decoupled from code. Developed C# Unity apps for Android, Windows, and WebGL with WebSocket-based Supabase Realtime flows. Set up CI/CD pipelines and an auto-update system for builds and patches.

JavaScript TypeScript CI CD Pipelines Android Web Firebase Unity C#Supabase

Multimedia Engineer

Politecnico Grancolombiano

Apr 2021 - May 2024 (3 years 1 month)

Built and maintained ASP.NET Core REST APIs with SQL Server and MongoDB for data storage, validation, simulation results, and reporting. Refactored legacy .NET APIs for performance and maintainability. Developed 2D/3D educational simulators in Unity and C# for WebGL, synced with the backend to track user progress and academic data. Built admin modules for data filtering, reporting, and export.