Principal Technical Lead - .Net - Pro-AI coding

Stelfox Tech Recruitment; Ireland; Hybrid; EUR 130,000 - 170,000; Full time

Job summary

Stelfox is partnering with a Fintech provider in Cork City to modernise their product and platform, embracing AI-first development to extend Agentic AI services for financial institutions. The Principal Technical Lead will drive the modernisation, decompose legacy systems, and own the hardest problems—writing production code daily and guiding engineering practices.

The role focuses on leading modernisation, bridging legacy and modern architectures, and leveraging AI to accelerate product

Qualifications

• Expert-level experience with .NET/C# and modern patterns (async/await, DI, clean architecture).
• Cloud-native development on Azure; AWS/GCP transferable.
• Database design, optimization, and migration for high-volume systems.

Responsibilities

• Lead the modernisation—decompose legacy monoliths into scalable services.
• Write production code daily and review PRs; no excessive meetings.
• Raise the technical bar with testing, patterns, and automation; ship incrementally.

Skills

NET/C#

Azure

API design

Testing strategies

Refactoring

Microservices

CI/CD

Legacy modernization

Tools

Azure DevOps

Job description

Stelfox is partnering with a Fintech provider located in Cork City who are going through a product & platform modernisation process as they truly embrace the power of AI-first development to help extend Agentic AI services on top of their existing product line being deployed with leading financial institutions across the U.S market.

We are looking to add a Principal Technical Lead to help drive the modernisation and take ownership of the hardest problems - decomposing legacy systems, building modern replacements and ensuring transition happens incrementally.

Your role will:

• Lead the modernisation - decomposing legacy monolithic patterns into clean, testable and maintainable services.
• Write Code daily - you are not in meetings all day, you will be writing production code and reviewing PRs.
• Raise the technical bar - Good coding standards, testing practices and engineering patterns.
• Ship Incrementally - without big-bang rewrites.
• Bridge Legacy & Modern - navigate the reality of a production system serving enterprise customers.
• Leverage AI to accelerate - identify opportunities where agentic capabilities can accelerate the modernisation process or unlock new product capabilities.

Experience & Skills requirement:

• Expert-level experience with .NET / C#, deep understanding of frameworks, modern patterns (async/await, dependency injection, clean architecture, domain modeling).
• Cloud-native development on Azure (AWS/GCP are transferable)
• Database design, optimization, and migration strategies for high-volume systems
• CI/CD pipelines and automated deployment practices
• Designing scalable APIs and managing versioning and backward compatibility
• Experience implementing testing strategies across unit, integration, and end-to-end testing layers
• Large-scale refactoring and modernization approaches such as incremental decomposition or strangler patterns

Please note, this position is located in Cork with 3 days in office, 2 remote from home, so candidates will need to be either located in or near Cork or be willing to relocate for this opportunity.