Senior .NET Developer (VB.NET / ASP.NET) – Web & Legacy Systems

BA Insurance Systems; Ku-ring-gai; Hybrid; AUD 140,000 - 210,000; Full time

Benefits offered by this job

Work-from-home 2–3 days/week

Internal training on legacy systems &

Direct access to Technical Director

Job summary

BA Insurance Systems seeks a hands-on Senior .NET Developer to own our ASP.NET web applications and the legacy systems behind them. You will work on VB.NET with possible C# adoption, and contribute AI-enabled features using LLMs.

Expect a stable codebase, direct access to the Technical Director, and a long-term role in a growing, established software team. You’ll handle production issues, collaborate across IIS/Windows Server environments, and engage in internal training on legacy systems and AI

Qualifications

• 5+ years' commercial development experience, mainly on Microsoft/.NET technologies.
• Strong ASP.NET, VB.NET (or C# with willingness to learn VB.NET) and Visual Studio.
• HTTP-based web services, XML and JSON.
• IIS and Windows Server administration for deployment and troubleshooting.
• Some exposure to VB6 - reading and debugging legacy code (training provided).
• Experience owning production issues on business-critical applications.
• Interest in applying Generative AI to existing business applications.
• Permanent, long-term position with a stable company.
• 2-3 days work from home per week.

Responsibilities

• Maintain, enhance and troubleshoot ASP.NET / .NET Framework 4.8 web applications.
• Investigate and resolve production issues across the application, IIS and Windows Server.
• Develop and maintain XML-over-HTTP web services and integrations with external systems.
• Design and integrate AI-enabled features using LLM APIs, prompt design and tool/function calling.

Skills

ASP.NET

VB.NET

C#

Visual Studio

IIS

Windows Server

XML

JSON

Debugging

AI/LLM

Tools

XML-over-HTTP

Web Services

VB6 (reading)

VB.NET code-behind

Job description

We're looking for a hands-on Senior .NET Developer. You'll own our ASP.NET web applications and the legacy systems behind them. Over time, you'll help us add AI-enabled features. Our applications run on ASP.NET (.NET Framework 4.8) with VB.NET code-behind. They talk to other systems through simple XML-over-HTTP web services. You'll report directly to the Technical Director and work with a stable codebase that has real users depending on it, so the emphasis is on understanding it deeply, improving it thoughtfully, and modernising where it adds value rather than rewriting for its own sake. Our primary language is VB.NET. If you're a strong C# developer who is happy to work in VB.NET, we'd like to hear from you - the transition is straightforward and we'll support it.

Key responsibilities

• Maintain, enhance and troubleshoot ASP.NET / .NET Framework 4.8 web applications
• Investigate and resolve production issues across the application, IIS and Windows Server
• Develop and maintain XML-over-HTTP web services and integrations with external systems
• Design and integrate AI-enabled features using LLM APIs, prompt design and tool/function calling

About you

• 5+ years' commercial development experience, mainly on Microsoft/.NET technologies
• Strong ASP.NET, VB.NET (or C# with willingness to learn VB.NET) and Visual Studio
• HTTP-based web services, XML and JSON
• IIS and Windows Server administration for application deployment and troubleshooting
• Some exposure to VB6 - you won't be writing new VB6 applications, but you will need to be comfortable reading and debugging legacy VB6 code when issues arise (training provided)
• Experience owning production issues on business-critical applications
• Strong debugging and analytical skills, and the ability to work independently in an established codebase
• Comfortable learning unfamiliar and legacy technologies
• A genuine interest in a long-term role and in applying Generative AI to existing business applications
• Permanent, long-term position with a stable, established business
• 2-3 days work from home per week
• Internal training on our legacy systems and on AI development
• Direct access to the Technical Director and genuine ownership of your work
• Occasional on-call for production issues - in practice this is extremely rare

About us

We are an established software company of 20-30 people. We build tools that let developers create web applications on various database platforms, and we maintain a suite of established, business-critical web and legacy applications for our customers.