Principal Engineer

Stelfox Tech Recruitment; Cork; Hybrid; EUR 120,000 - 150,000; Full time

Job summary

Stelfox Tech Recruitment is partnering with a Cork-based Fintech provider to modernise their product and platform, embracing AI-first development to enhance Agentic AI services across their offerings deployed to US financial institutions.

We are seeking a Principal Software Engineer / Tech Lead to own the hardest problems—decomposing legacy systems, building modern replacements, and guiding incremental transition with a strong emphasis on code quality, tests, and scalable APIs.

Qualifications

• Expert-level experience with .NET/C# and modern patterns such as async/await, DI and clean architecture.
• Cloud-native development on Azure; AWS/GCP transferable.
• Database design, optimization, and migration for high-volume systems.
• CI/CD pipelines and automated deployment practices.

Responsibilities

• Lead the modernisation by decomposing legacy monolithic patterns into services.
• Raise the technical bar with coding standards, testing practices and engineering patterns.
• Bridge Legacy & Modern by aligning production systems with enterprise requirements.
• Leverage AI to accelerate modernization and unlock new product capabilities.

Skills

NET/C#

Azure

Database design

CI/CD pipelines

API design

Testing strategies

Refactoring

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 Software Engineer / Tech 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.
• Raise the technical bar - Good coding standards, testing practices and engineering patterns.
• 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.