Senior Full-Stack Engineer: .NET Core Microservices + AWS

Rapsys Technologies Pte Ltd.; Singapore; On-site; SGD 120,000 - 180,000; Full time

Job summary

Rapsys Technologies Pte Ltd. is seeking a seasoned Software Engineer (Full Stack) to design, implement, and optimize robust microservices-based solutions. The role covers both backend and frontend work, leveraging .NET Core, Java, EF, Docker, AWS, and modern frontend tech.

You will work on legacy migrations, security, and performance initiatives in a Singapore office setting. Ideal candidates have 5+ years of hands-on experience across full stack development, microservices, and cloud-based

Qualifications

• Proven professional experience on .NET Core stack.
• Strong proficiency in .NET Core, .NET 8, C#, Java and related backend technologies.
• Experience building microservices architecture and implementing event-driven design patterns.
• Proficiency in Entity Framework (EF) for database management.
• Familiarity with Docker and containerization principles.
• Knowledge of Domain-Driven Design (DDD) principles and their application in backend development.
• Experience implementing OAuth for authentication and authorization.
• Understanding of security best practices and their application in backend development.
• Hands-on experience with AWS services such as S3, Lambda, API Gateway, RDS, etc.
• Proficiency in frontend technologies such as HTML, CSS, and JavaScript, ASP.NET and WebForms.
• Experience writing unit tests and maintaining a design system with Storybook.
• Strong problem-solving skills and attention to detail.
• Excellent communication and collaboration skills.
• Knowledge and experience in utilizing generative AI to develop and review codes via Spec Driven Development (SDD).
• Hands-on experience with legacy .NET Framework (4.x) applications, including maintenance and incremental modernisation.
• Experience with Oracle databases, including query optimisation and integration with .NET applications.
• Proficiency in deploying and configuring applications on IIS and Windows Server, with working knowledge of Web.config transformations for environment-specific deployments.
• Hands-on experience with Java Quarkus framework, including building and deploying cloud-native microservices, with working knowledge of OpenTelemetry for distributed tracing and observability.
• Preferably more than 5 years of experience as a full stack software engineer.
• Experience working in both Unix and Windows operating environments are preferred.
• AWS certification (e.g., AWS Certified Developer, AWS Certified Solutions Architect).
• Experience with Node.js for server-side development.
• Familiarity with RDS databases such as MSSQL.
• Knowledge of CI/CD pipelines and DevOps practices.
• Understanding of Agile development methodologies.
• Experience with event-driven development patterns and architectures, as well as frontend development using React or other SPA frameworks.

Responsibilities

• Design, develop, and maintain microservices architecture using .NET Core, .NET8 and Java.
• Implement event-driven architecture to enable seamless communication between microservices.
• Utilize Entity Framework (EF) for efficient database interactions and management.
• Containerize applications using Docker for scalability and deployment flexibility.
• Apply Domain-Driven Design (DDD) principles to ensure clean and modular code architecture.
• Implement OAuth for secure authentication and authorization.
• Develop and enforce security best practices to safeguard sensitive data and systems.
• Utilize AWS services such as S3, Lambda, API Gateway, RDS, etc., for backend development.
• Develop RESTful APIs endpoints to facilitate communication between the frontend and backend.
• Apply Spec Driven Development (SDD) concepts in development of code via ClaudeAI technologies.
• Support and maintain legacy .NET Framework (4.x) applications, including migration pathways to modern .NET where applicable.
• Manage application hosting and deployment on IIS and Windows Server environments, including environment-specific configuration management using config transformations.
• Develop responsive and user-friendly web applications using ASP.NET, including WebForm applications.
• Generate and review unit tests using generative AI to ensure code quality and reliability.
• Create reusable UI components and maintain a consistent design using Storybook.
• Collaborate closely with UX/UI designers to implement intuitive and visually appealing interfaces.
• Troubleshoot and debug issues across the stack, ensuring smooth application operation.
• Optimize application performance and scalability for a seamless user experience.

Skills

NET Core

C#

Java

Event-driven design

EF (Entity Framework)

Docker

DDD

OAuth

Security best practices

AWS

HTML/CSS/JavaScript

Storybook

Unit testing

AI-assisted code review

Legacy .NET 4.x

IIS/Windows Server

Java Quarkus

OpenTelemetry

React/SPA frameworks

Tools

Docker

Oracle DB

Quarkus

OpenTelemetry

Job description

Rapsys Technologies Pte Ltd. is seeking a seasoned Software Engineer (Full Stack) to design, implement, and optimize robust microservices-based solutions. The role covers both backend and frontend work, leveraging .NET Core, Java, EF, Docker, AWS, and modern frontend tech.

You will work on legacy migrations, security, and performance initiatives in a Singapore office setting. Ideal candidates have 5+ years of hands-on experience across full stack development, microservices, and cloud-based