Senior Full Stack .NET and Web Developer

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
2. Have you led the design, architecture, or modernization of a large-scale enterprise software platform? • Yes • No If yes, please briefly describe the project.
3. 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
4. What is your level of experience designing and implementing REST API architectures? • None • Basic • Intermediate • Advanced • Expert / Architect
5. 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
6. 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.
7. Which industries have you developed enterprise software for? (Select all that apply) • Manufacturing • ERP • Wholesale Distribution • Warehousing • Logistics / Supply Chain • Accounting / Finance • Retail • Other
8. Have you been responsible for mentoring developers or leading a software development team? • No • Informal Mentoring • Technical Lead • Development Manager • Solution Architect / Principal Engineer
9. Please describe the largest software system you have designed, modernized, or maintained, including: • Number of users • Technology stack • Your role • Key business functions supported
10. 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?