Full-Stack Software Engineer (.NET/Java, Microservices, AWS)

Rapsys Technologies Pte Ltd.; Singapore; On-site; SGD 70,000 - 110,000; Full time

Job summary

Rapsys Technologies Pte Ltd. is seeking a Software Engineer (Full Stack) to design, develop, and maintain microservices-driven web applications for financial industry solutions.

You will work in an agile team on backend services using .NET Core/.NET 8 and Java, with Docker-based deployments and AWS cloud integration. You will collaborate with UX/UI designers, implement OAuth security, and ensure code quality with unit tests and AI-assisted reviews.

Qualifications

• Proven experience with .NET Core stack and microservices.
• Strong skills in .NET Core, .NET 8, C#, Java and related backend technologies.
• Experience building microservices and event-driven designs.
• Proficiency with Entity Framework and database management.
• Familiarity with Docker and containerization.
• Knowledge of DDD principles and backend design.
• Experience implementing OAuth and secure authentication.
• Understanding of security best practices in backend development.
• Hands-on with AWS services (S3, Lambda, API Gateway, RDS).
• Frontend basics: HTML, CSS, JavaScript; ASP.NET and WebForms.
• Experience with unit tests and design systems (Storybook).
• Knowledge of OpenTelemetry and observability.
• Experience migrating legacy .NET Framework apps; IIS/Windows Server deployments.
• Experience with Oracle databases and SQL performance tuning.
• Familiar with Quarkus for cloud-native microservices.

Responsibilities

• Design, develop, and maintain microservices architecture using .NET Core, .NET 8 and Java.
• Implement event-driven architecture for inter-service communication.
• Use EF for efficient database interactions and management.
• Containerize applications with Docker for scalability and deployment flexibility.
• Apply DDD principles for clean, modular code structure.
• Implement OAuth for secure authentication and authorization.
• Enforce security best practices to protect data and systems.
• Leverage AWS services (S3, Lambda, API Gateway, RDS) for backend development.
• Develop RESTful APIs to connect frontend and backend.
• Apply Spec Driven Development (SDD) using Claude AI tooling.
• Support and migrate legacy .NET Framework (4.x) apps; plan modernisation.
• Manage hosting and deployment on IIS/Windows Server with config transforms.

Skills

.NET Core

C#

Java

Microservices

DDD

OAuth

Security best practices

AWS

Frontend basics (HTML/CSS/JS)

Unit tests

Education

Bachelor's degree in Computer Science

Tools

Docker

OpenTelemetry

Oracle databases

IIS / Windows Server

WebForms

ASP.NET

Quarkus

Storybook

Claude AI / SDD tooling

Job description

Rapsys Technologies Pte Ltd. is seeking a Software Engineer (Full Stack) to design, develop, and maintain microservices-driven web applications for financial industry solutions.

You will work in an agile team on backend services using .NET Core/.NET 8 and Java, with Docker-based deployments and AWS cloud integration. You will collaborate with UX/UI designers, implement OAuth security, and ensure code quality with unit tests and AI-assisted reviews.