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 • Market-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
How many years of commercial software development experience do you have using .




NET technologies?
• Less than 5 years • 5-10 years • ***** 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 modern 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)
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