Principal Software Engineer

Principal EngineerLondon | Hybrid | PermanentSalary: Up to £140,000 + Bonus & BenefitsHarrington Starr is partnering with a leading financial technology firm to hire a Principal C# Software Engineer based in London.This is a senior technical leadership role focused on real-time trading technology, platform modernisation and re-architecture, combining hands-on engineering, architecture and mentoring.The Role:Shape the technical roadmap and platform re-architecture strategyDesign and evolve low-latency, event-driven distributed systemsLead platform development through to production and improve scalability, resilience and performanceDrive improvements across automation, observability, CI/CD and developer productivityPartner with Engineering, Product and Operations to deliver practical technical solutionsMentor engineers and champion engineering standards, best practices and continuous improvementWhat We're Looking For:Strong C#/.NET software engineering experienceProven experience building scalable, high-performance distributed systemsStrong understanding of real-time and low-latency architectureExperience leading modernisation, migration or re-architecture programmesExperience with cloud-native architectures, APIs, event-driven systems and CI/CDFinancial markets experience, ideally across electronic trading, OTC derivatives, fixed income, FX or similar, with strong technical leadership skillsBenefits:Up to £140,000 base salary + discretionary bonus25 days annual leave + bank holidaysHybrid and flexible workingPrivate Medical Insurance and Life InsurancePension and Employee Assistance ProgrammeIf you’re a Principal-level C# engineer looking to shape architecture, modernise complex platforms and work on real-time financial technology, we’d love to hear from you.