Senior Product Engineer – C#/.NET & AI in Newcastle upon Tyne

We're partnering with a major global enterprise SaaS organisation making a significant investment in Applied AI across its established product portfolio. This is not a Data Scientist, ML research or proof-of-concept role. It's a hands-on software engineering position for somebody who wants to take AI from idea through to production — building capabilities that reach real customers and sit inside business-critical software.

The Opportunity

You'll join an established Product Engineering function tasked with embedding modern AI capability into mature C#/.NET platforms. The challenge isn't simply getting an LLM to work. It's making AI reliable, measurable, maintainable and genuinely useful in production.

You will:

• Build and ship AI-powered features within established C#/.NET products
• Design prompts, context strategies and structured LLM outputs
• Integrate commercial LLM APIs into production software
• Prototype rapidly and turn successful concepts into robust functionality
• Build evaluation into features from the outset
• Manage accuracy, latency, token costs, fallbacks and failure scenarios
• Implement appropriate logging and monitoring
• Work alongside Software Engineers, Product Managers and domain specialists
• Evaluate different models and providers based on quality, cost and performance
• Help establish Applied AI engineering standards across the wider organisation

Technology: C# | .NET | Generative AI | LLM APIs | Prompt Engineering | RAG | Vector Search | Embeddings | GitHub Copilot | Cursor

What We're Looking For

First and foremost, you need to be a strong commercial C#/.NET Software Engineer. Alongside this, we're looking for genuine hands-on experience building with Large Language Models professionally — not simply personal projects or online courses. Ideally you'll demonstrate:

• Experience working within established, business-critical codebases
• Commercial LLM integration
• Prompt and context engineering
• Structured AI outputs
• Testing/evaluation of LLM responses
• Strong software engineering fundamentals
• Experience taking ideas from prototype through to production
• Daily use of AI-assisted development tools
• Experience with RAG, agentic workflows, tool calling, vector databases, embeddings or multiple LLM providers would be particularly valuable.

Why This One?

This is an opportunity to work on Applied AI where the output actually matters. You'll be introducing AI into established enterprise products with existing customers, meaningful datasets and real-world commercial problems to solve. The organisation wants engineers who can experiment quickly but engineer properly — people who understand that getting an impressive AI demo working is the easy part; building something customers can genuinely trust is where the interesting engineering begins. You'll have significant freedom to explore emerging technology while still operating within a mature Product Engineering environment. If you're a .NET engineer who has genuinely embraced Applied AI and wants to build production technology rather than endless prototypes, this is an opportunity worth exploring.