Existco is seeking an experienced Senior Full Stack .NET Developer to lead the next generation redesign and modernization of our ExPCS Existco Plant Control System (ExPCS), a comprehensive ERP and manufacturing platform used within the food manufacturing, processing, wholesale distribution, and logistics industries.

We are looking for a highly capable senior developer and software architect who can help transform a mature, business-critical platform built on VB.NET, WinForms, Xamarin, SQL Server, and Windows Services into a modern API-driven architecture leveraging web, desktop, mobile, cloud, and distributed technologies.

You will work directly with executive leadership, product owners, and customers to shape the long-term technical direction of the platform.

Key Responsibilities

- Lead the technical architecture and modernization of the Existco Plant Control System platform
- Design scalable backend services and API infrastructure
- Build modern desktop, web, and mobile applications
- Refactor legacy applications into service-oriented architecture
- Design and implement domain-driven business objects and repositories
- Improve existing application performance, reliability, and maintainability
- Develop integration frameworks for third-party platforms
- Mentor junior developers and provide technical leadership
- Participate in strategic product planning and roadmap development
- Collaborate with business stakeholders to translate complex operational requirements into software solutions
- Maintain and migrate existing platform until depreciation.

Required Skills & Experience

- 10+ years commercial software development experience
- Strong C# and .

NET development expertise

- Experience designing large-scale enterprise applications
- Strong SQL Server and database design knowledge
- Experience with REST API development
- Experience with Azure cloud services
- Strong understanding of software architecture patterns
- Experience with object-oriented design principles
- Knowledge of source control, CI/CD, and automated deployments
- Understanding of accounting principles, ERP Systems and Warehouse Management Systems
- Excellent problem-solving and communication skills

Highly Desirable Skills

Event-Driven Systems

- Vue.js 3
- Electron
- Azure App Services
- Microsoft MAUI
- Node.js




- TypeScript
- Microservices Architecture
- Enterprise Database systems
- Experience and strong understanding Manufacturing, ERP, Accounting, Logistics, Supply Chain, or Warehouse Management Systems
- Mobile Offline Synchronization Architecture
- Multi-site enterprise application development

What Success Looks Like

Within your first 12 months, you will help define and execute:

- The migration strategy from the legacy platform
- Design of the new API and service layer
- Modernization of desktop applications
- Mobile application architecture roadmap
- Scalable integration platform for customers and partners
- Improved cloud deployment and monitoring capabilities

Why Join Existco?

- Opportunity to architect a major business-critical platform from the ground up
- Work directly with executive leadership and product stakeholders
- Influence technology decisions and product direction
- Exposure to cloud, desktop, web, mobile, and enterprise architecture
- Long-term product ownership and technical leadership opportunities
- Competitive salary package based on experience

Salary Guide

$100,000 - $120,000 + Superannuation

(Dependent on experience, architecture capability, and demonstrated leadership)

How to Apply

Please submit your resume together with a cover letter outlining:

- Significant software architecture projects you have led
- Enterprise systems you have designed or modernized
- Experience with .

NET, Azure, API architecture, and modern frontend frameworks

- Examples of distributed, scalable, or mission-critical applications you have built

Join us and help shape the future of the ExPCS Existco Plant Control System platform. We are looking for a developer who can think strategically, architect pragmatically, and build exceptional software that solves real-world business challenges.

Qualification Questions

1.



How many years of commercial software development experience do you have using . NET technologies?

- Less than 5 years
- 5-10 years
- 10-15 years
- 15+ years

- Have you led the design, architecture, or modernization of a large-scale enterprise software platform?

- Yes
- No

If yes, please briefly describe the project.

- Which of the following technologies have you used professionally? (Select all that apply)

- C# • .

NET Framework / . NET Core

- SQL Server
- Azure
- REST APIs
- WinForms
- VB.NET
- MAUI / Xamarin
- Vue.js
- Electron
- Node.js
- TypeScript

- What is your level of experience designing and implementing REST API architectures?

- None
- Basic
- Intermediate
- Advanced
- Expert / Architect

- Have you designed or implemented solutions using any of the following architectural patterns? (Select all that apply)

- Domain-Driven Design (DDD)
- CQRS
- Event-Driven Architecture
- Microservices
- Repository Pattern
- None of the above

- What experience do you have migrating legacy applications to contemporary architectures? Please provide a brief example including technologies used and your role in the project.

- Which industries have you developed enterprise software for? (Select all that apply)

- Manufacturing
- ERP
- Wholesale Distribution
- Warehousing
- Logistics / Supply Chain
- Accounting / Finance
- Retail
- Other

- Have you been responsible for mentoring developers or leading a software development team?

- No
- Informal Mentoring
- Technical Lead
- Development Manager
- Solution Architect / Principal Engineer

- Please describe the largest software system you have designed, modernized, or maintained, including:

- Number of users
- Technology stack
- Your role
- Key business functions supported

- This role requires working directly with executive leadership and helping define long-term product strategy. Which best describes your experience?

- Developer only
- Senior Developer
- Technical Lead
- Solution Architect
- Principal Architect / CTO-level responsibilities

Bonus Question (Highly Recommended)

1. Why are you interested in leading the modernization of the ExPCS platform, and what would be your high-level approach to transforming a legacy VB.NET/WinForms system into a modern API-first architecture?

📌 Senior Full Stack .NET and Web Developer (Perth)
🏢 Existco
📍 Perth