.NET/C# full stack software engineer
Resume:
JOHHANNAS REYN
Software Engineer
https://www.linkedin.com/in/johhannas-reyn
********.*********@*****.***
Temecula, CA 92592
SUMMARY
Experienced Full-Stack Engineer with 9 years of expertise in building scalable web applications using C#, ASP.NET Core/MVC, and modern frontend frameworks such as Blazor, Angular, and React. Proficient in designing robust backend architectures and developing microservices-based systems using .NET, Entity Framework, and Web APIs, enabling modular, maintainable, and scalable solutions. Skilled in optimizing database performance across MS SQL, PostgreSQL, Azure Cosmos DB, and MongoDB. Experienced in cloud solutions with Azure, as well as DevOps practices including CI/CD pipelines, Docker, and Kubernetes. Adept at Agile methodologies, collaborating with cross-functional teams, and delivering high-performance applications that drive business success.
SKILLS
Programming languages: C#, C++(11/14/17/20), JS/TS, Java, Python
Backend: .NET, ASP.NET Core/MVC, .NET MAUI, WPF, REST APIs, WebSockets, EF Core, Identity, SignalR, Spring Boot
Frontend: Angular, React, Vue, Blazor, Razor Pages, React Native, Bootstrap, HTML, CSS, jQuery
Database: MS SQL, PostgreSQL, MySQL, Azure Cosmos DB, MongoDB, Redis, Oracle, SQLite
Security Practices: OAuth, Keycloak, JWT, Role-based Access Control (RBAC), OWASP
Message Brokers & Event-Driven Systems: Azure Service Bus, RabbitMQ, Apache Kafka
Cloud: Microsoft Azure, AWS, GCP
Devops: Docker, Kubernetes, CI/CD (GitHub Actions, Jenkins, CircleCI), Terraform, Ansible, IIS, Nginx
Testing: MSTest, NUnit, xUnit
Agile: Kanban, Scrum, Test-Driven Development (TDD), Domain-Driven Design (DDD) E X P E R I E N C E
Senior .NET Full Stack Engineer
Altoros Labs United States (Contract)
09/2023 - 02/2025
Developed a cloud-based healthcare platform that enables online appointment booking, telemedicine consultations, and electronic medical records (EMR) management for hospitals and clinics, ensuring seamless interoperability with Epic EHR.
Designed and developed microservices architecture using ASP.NET Core Web API, ensuring scalability and modular service design.
Integrated Epic Systems using FHIR (Fast Healthcare Interoperability Resources) API, enabling secure synchronization of patient records, medical history, prescriptions, and lab results across hospitals and clinics.
Implemented RabbitMQ-based event-driven communication for handling asynchronous processes like appointment notifications, patient data updates (via Epic), and payment processing.
Utilized MS SQL Server with Entity Framework Core (EF Core) to design efficient, normalized databases and optimize transaction handling for high-volume operations.
Implemented stored procedures, indexing, and query optimizations to enhance database performance and reduce 2 / 4
latency.
Integrated Redis caching to enhance API response times and reduce database load.
Developed a telemedicine module using WebRTC, deployed on Azure Kubernetes Service (AKS) for scalable real-time video consultations. Integrated Epic EHR patient records into video consultations for doctors to access medical history during appointments.
Secured patient data by implementing JWT authentication, OAuth 2.0 (Google & Microsoft sign-in), AES-256 encryption, and ensuring HIPAA compliance for data storage and transmission.
Implemented Azure Monitor, Log Analytics, and Application Insights for real-time system monitoring and logging, ensuring proactive issue resolution.
Developed and optimized background job processing using Hangfire, ensuring efficient scheduling of tasks like Epic data synchronization, appointment reminders, and report generation.
Integrated Stripe and PayPal APIs for secure online payment processing and subscription management.
Implemented unit and integration tests using xUnit along with Moq for mocking, ensuring robust and maintainable code.
Led performance optimization efforts, including horizontal scaling via Azure Kubernetes Service (AKS) with auto-scaling policies, load balancing, and EF Core query tuning to handle high traffic efficiently.
Stack: C#, ASP.NET Core, Angular, Blazor, React Native, MS SQL, Redis, EF Core, RabbitMQ, Hangfire, Epic EHR, RESTful APIs, WebRTC, xUnit, Moq, Azure, AKS, Docker
.NET Full Stack Engineer
IT Minds LLC United States (Full-time)
12/2021 - 07/2023
Developed a team task management system to streamline task assignment, tracking, and collaboration, improving task completion efficiency by 40%.
Designed and implemented a RESTful API using ASP.NET Core (.NET 7) and Entity Framework Core (EF Core), ensuring scalable and maintainable backend architecture.
Integrated GraphQL API alongside RESTful services, enabling flexible and efficient data querying for frontend applications.
Developed real-time task updates and notifications using SignalR and Apache Kafka, ensuring seamless collaboration across distributed teams.
Implemented Swagger (OpenAPI) documentation for all APIs, enabling easier developer onboarding and API testing.
Implemented JWT-based authentication and OAuth (Google & Microsoft login), securing user access with role-based access control (RBAC) for Admins, Managers, and Employees.
Built a modern, responsive frontend using React (TypeScript) and Tailwind CSS, integrating Redux Toolkit for state management.
Developed a cross-platform mobile application using .NET MAUI, providing seamless task management across Windows, Android, and iOS.
Integrated Slack and Microsoft Teams notifications using web hooks, enabling seamless team communication for assigned tasks and updates.
Designed a reporting dashboard with task analytics, exportable in CSV/PDF format, providing managers with insights into task completion trends.
Implemented unit and integration tests using xUnit and Moq, ensuring code reliability and maintainability.
Led performance optimization efforts, reducing API response times by 40% through database indexing, caching strategies (Redis), and query optimization.
Stack: C#, .NET Core, EF core, SignalR, Apache Kafka, Swagger/OpenAPI, GraphQL, MS SQL, Redis, JWT & OAuth, React, 3 / 4
Redux, Tailwind CSS, .NET MAUI, xUnit, Moq, Docker, Kubernetes, CI/CD, MS Azure, AWS Lambda C#/.NET Full Stack Engineer
Cubix United States (Full-time) 12/2019 - 09/2021
Architected multi-language & data-rich web applications and developed modular & reusable components, led data migration efforts to ensure zero data loss, and managed & executed server upgrades & patching.
Enhanced accessibility and support for internationalization in applications using AngularJS and .NET framework.
Developed modular and reusable components in C#/.NET and WCF, applying design patterns to create maintainable and scalable solutions, optimized for deployment and simplified future enhancements.
Used Oracle PL/SQL to automate migration tasks, validate data integrity, and implement stored procedures and triggers that enforced business rules, ensuring system reliability and uninterrupted operations.
Created DTS Packages to import data from flat files into SQL Server, ensuring data accuracy and accessibility.
Utilized ADO.NET, LINQ to SQL, and Entity Framework to create efficient data access layers, making database interactions smooth and optimized.
Stack: C#, ASP.NET MVC, Entity, Razor, Angular, WCF services, Entity, LINQ, RESTful APIs, SQL server, NUnit, Azure, Docker, Jenkins
.NET/SQL Engineer
Cubix United States (Full-time)
09/2018 - 11/2019
Focused on API integration services, data management, and financial tools.
Developed a desktop application interface with WinForms & WPF.
Built APIs & integrations using SOAP, WCF services, and connected enterprise applications through MSMQ.
Created data-driven applications to manage & visualize enterprise data by using SSRS, Crystal Reports.
Optimized SEO and database queries, increasing traffic and enhancing app performance.
Resolved critical transaction bugs in 20k lines of C# code, restoring stability for 6,000 users.
Stack: C#, ASP.NET, WCF Service, WPF, NServiceBus, Identity Server, AJAX, Telerik, SOAP, REST, MSMQ, RabbitMQ, PostgreSQL, AWS, Jenkins
Frontend Developer 08/2017 - 08/2018
Cubix United States (Contract)
Worked on developing and maintaining a cross-platform mobile and web application to enhance customer engagement.
Built and optimized React and React Native applications with a focus on performance and scalability.
Collaborated with backend developers and UI/UX designers to create responsive and intuitive interfaces.
Implemented state management using Redux and optimized component reusability.
Ensured cross-browser compatibility and mobile responsiveness for a seamless user experience.
Stack: React, React Native, Redux, JavaScript, TypeScript, HTML, CSS E D U C A T I ON
University of California, Irvine 08/2015 - 06/2017
Bachelor’s degree in Computer Science
College of the Canyons, Santa Clarita 08/2013 - 06/2015
Associate of Science Degree in Computer Science - Summa cum laude, Top 1%
Associate of Science Degree in Mathematics - Magna cum laude
Associate of Science Degree in Computer Science - Cum laude 4 / 4
Contact this candidate