AI Software Engineer – C# .NET

Apache Associates; Hungerford; On-site; GBP 60,000 - 95,000; Full time

Job summary

Apache Associates is seeking an AI Software Engineer with strong C# .NET experience to turn emerging AI capabilities into production-ready features for our SaaS products. You will design prompts, integrate LLMs, and work across product teams to ensure robust, scalable solutions.

You’ll prototype quickly while maintaining engineering discipline—focusing on accuracy, latency, cost and monitoring to deliver reliable AI-powered capabilities that align with business goals.

Qualifications

• Proven commercial experience building AI-enabled software.
• Experience with AI development in SaaS products is a plus.
• Experience with .NET and C# in production.

Responsibilities

• Design and build prompts, context strategies and LLM integrations for real-world product features.
• Develop in C# .NET, integrating AI capabilities into established codebases.
• Create production-grade AI services with robust error handling, fallbacks, monitoring and logging.
• Prototype new ideas quickly and turn successful experiments into robust production features.
• Develop structured approaches to evaluating LLM outputs, using real business scenarios and measurable results.
• Work with LLM APIs across different providers and balance quality, cost and latency.
• Use AI coding tools such as GitHub Copilot, Cursor or equivalent as part of your day-to-day development.
• Collaborate with Product and subject matter experts to understand the business problem before deciding on the technical solution.
• Ensure AI features are developed with accuracy, safety and data handling in mind.

Skills

C# .NET development

Large Language Models

Prompt engineering

Context engineering

Structured outputs

LLM integrations

GitHub Copilot

Cursor

Tools

GitHub Copilot

Cursor

Job description

Apache Associates are currently working with an innovative SaaS organisation that is investing heavily in AI across its products. We’re looking for anAI Software Engineer with strong C# .NET experience to join the team and help turn emerging AI capabilities into genuine, production-ready product features.

This is an ideal opportunity for a developer who combinesstrong software engineering fundamentals with hands‑on LLM experience and enjoys working in an environment where things move quickly.

You’ll be taking AI concepts from initial idea and experimentation through to fully integrated, evaluated features within established .NET products.

The Role

You’ll be responsible for building AI-powered capabilities across the product portfolio, working withLLMs, prompt engineering, context design and structured outputs, while ensuring everything you build is robust enough for production.

You’ll be expected to prototype quickly, but equally importantly, understand where engineering discipline is essential. That means thinking aboutaccuracy, reliability, latency, cost, monitoring, fallbacks and evaluation rather than simply getting an AI feature to work in a demo.

You’ll work closely with existing engineering teams, Product Managers, Product Owners and subject matter experts to understand the business problem before deciding on the technical solution.

Key Responsibilities

• Design and build prompts, context strategies and LLM integrations for real‑world product features.
• Develop primarily inC# .NET, integrating AI capabilities into established codebases.
• Build production‑grade AI services with appropriate error handling, fallbacks, monitoring and logging.
• Prototype new ideas quickly and turn successful experiments into robust production features.
• Develop structured approaches toevaluating LLM outputs, using real business scenarios and measurable results.
• Work with LLM APIs across different providers and make pragmatic decisions around quality, cost and latency.
• Use AI coding tools such asGitHub Copilot, Cursor or equivalent as part of your day‑to‑day development.
• Work alongside existing engineering teams to ensure your solutions fit established coding standards, architecture and deployment pipelines.
• Keep pace with the rapidly changing AI ecosystem and share new approaches and learning with colleagues.
• Work with Product and subject matter experts to understand the underlying business problem rather than simply responding to a technical requirement.
• Ensure AI features are developed with appropriate consideration foraccuracy, safety and data handling.

Skills and Experience Required

You’ll need to be a strong software engineer first and foremost, with genuine commercial experience building with AI.

We’re particularly interested in people who can demonstrate:

• Strongcommercial C# .NET development experience, ideally working within established and potentially long‑lived codebases.
• Hands‑on experience building applications usingLarge Language Models, beyond tutorials or experimentation.
• Strong knowledge ofprompt engineering, context engineering and structured outputs.
• Experience taking ideas from concept through to working software quickly.
• Experience evaluating or testing LLM outputs using structured approaches, datasets or real‑world business scenarios.
• Daily experience using AI‑assisted development tools such asGitHub Copilot, Cursor or similar.
• A pragmatic approach to software engineering – knowing when to move quickly and when production quality cannot be compromised.
• The ability to understand and articulate thebusiness problem behind the technology you’re building.

It would be advantageous if you also have experience with:

• RAG (Retrieval‑Augmented Generation)
• Agentic workflows and tool use
• Vector databases/search and embeddings
• LLM APIs from multiple providers
• AI evaluation frameworks and automated quality pipelines
• Modernising or extending long‑established software platforms
• SaaS environments
• Distributive trades, rental, retail, automotive aftermarket or garage management

This isn’t a role where you’ll spend months working on theoretical AI projects that never reach customers.

You’ll have the opportunity tobuild, ship and see your work used in real products. The expectation is that successful ideas can move from concept to production in weeks, while still meeting the standards expected of business‑critical software.

You’ll also have the opportunity to influence how AI is adopted across the wider engineering organisation, sharing your knowledge and helping other developers understand what genuinely works.

Within your first six months, you'll ideally have:

• Shipped an AI capability into an established product with meaningful evaluation behind it.
• Taken an AI idea from concept to customers within weeks rather than quarters.
• Used evaluation data to influence product or technical decisions – including being prepared to stop something that simply isn’t good enough.
• Introduced new AI development techniques that other engineers have adopted.
• Demonstrated a clear understanding of the commercial problem you’re solving, not just the technology you’re using.

If you’re a C# .NET developer who is already building with LLMs and wants to work somewhere that is genuinely putting AI into production, we’d be very interested in hearing from you.