Senior Software Developer

Walker Smith; Christchurch; On-site; NZD 120,000 - 160,000; Full time

Job summary

Walker Smith in Christchurch is seeking a Senior Software Developer to join a growing team. You will be the go-to for hard design decisions on integration, AI features, and how to ship safe, scalable backend services in C# and .NET behind AI agents.

You'll influence engineering practices as AI changes delivery speed and review scope, mentor mid-level engineers, and partner with analysts to separate valuable AI use cases from hype.

Qualifications

• 5+ years of commercial experience in C# and .NET, with senior ownership.
• Deep SQL Server knowledge, including performance tuning.
• Cloud experience with modern platforms.
• Practical AI delivery using LLM APIs and AI-enabled features.
• Proven mentoring and rigorous code review experience.
• Strong communication with non-technical stakeholders.
• Experience in integration-heavy systems.

Responsibilities

• Designing and building backend services and APIs in C# and .NET behind AI agents, conversational tools and automation across several business units
• Making design decisions on how new AI features sit within a complex, integration-heavy platform
• Building on an in-house language model and modern tools
• Owning review standards for AI-generated code, including manual first reviews, and helping the team catch what AI tends to get wrong, such as inefficient queries and database locking
• Coaching mid-level developers and lifting the capability of the wider team
• Working with analysts and business leaders to separate genuinely valuable AI use cases from merely exciting ones
• Balancing new feature delivery with keeping the existing estate healthy, with realistic estimates

Skills

C# and .NET

SQL Server

Cloud experience

AI delivery (LLM APIs)

Mentoring

Code review

Communication

Integration-heavy systems

Job description

The Company

Our client is a technology-led organisation operating across multiple markets, built on a platform that pulls data and services together from a large network of external suppliers. Engineering stays in-house on a modern stack, with a proprietary AI layer on top that is moving from pilot to core capability. Several internal tools are being consolidated into a single platform. They take AI-assisted development seriously and with discipline, and want senior engineers who know where it helps and where it needs a human check.

The Role

We are seeking a Senior Software Developer to join a growing team in Christchurch. You will be the person other developers turn to for the hard calls: how to design an integration, how to structure an agent, whether a piece of generated code is safe to ship. The role is hands-on and backend-focused, with real influence on engineering practice at a time when AI is changing both the speed of delivery and the volume of code to review.

What You'll Be Doing

• Designing and building backend services and APIs in C# and .NET behind AI agents, conversational tools and automation across several business units


• Making design decisions on how new AI features sit within a complex, integration-heavy platform


• Building on an in-house language model and modern tools


• Owning review standards for AI-generated code, including manual first reviews, and helping the team catch what AI tends to get wrong, such as inefficient queries and database locking


• Coaching mid-level developers and lifting the capability of the wider team


• Working with analysts and business leaders to separate genuinely valuable AI use cases from merely exciting ones


• Balancing new feature delivery with keeping the existing estate healthy, with realistic estimates

Skills and Experience We're Looking For

• 5+ years' commercial experience in C# and .NET, with a record of senior ownership


• Deep SQL Server knowledge, including performance tuning


• Cloud experience


• Practical AI delivery, such as LLM APIs, agents or AI-enabled products shipped to production, with examples that hold up under technical questioning


• A track record of mentoring and rigorous code review


• Strong communication skills, including explaining trade-offs to non-technical stakeholders


• Experience in integration-heavy systems is advantageous

This position is based in Christchurch. If you're a senior developer who wants to apply AI properly on a complex, real platform and help set the standard for how a team builds with it.