Principal Software Engineer - (C# and the .NET Core ecosystem, Python) - Hybrid

FactSet•Norwalk, CT

5d•$165,000 - $215,000•Hybrid

About The Position

FactSet is seeking an accomplished Principal Software Engineer to join the core team responsible for its mission-critical Investment Book of Record (IBOR) platform. This platform serves as the definitive source of truth for all positions, transactions, and cash. The role involves being a key technical contributor, responsible for designing, building, and enhancing the services and interfaces that ensure the IBOR is reliable, scalable, and performant.

Requirements

10+ years of professional software engineering experience.
Expert-level proficiency in C# and the .NET Core ecosystem for building enterprise-grade backend systems.
Strong professional experience with Python for data analysis, scripting, or backend services.
Significant experience in the financial services industry, with a strong grasp of the trade lifecycle, financial instruments (equities, fixed income, derivatives), and position management concepts.
Experience building and consuming RESTful APIs and a solid understanding of software design patterns.
Bachelor's degree in Computer Science, Engineering, Mathematics, or a related field.

Nice To Haves

Direct experience working on an IBOR or Portfolio Management System
Experience with cloud platforms (AWS) and containerisation technologies (Docker/ ECS).
Experience working with ServiceStack

Responsibilities

Design, develop, and maintain robust backend services and APIs using C# (.NET Core), focusing on high throughput and low latency.
Build data processing pipelines, reconciliation tools, and analytical scripts using Python, leveraging libraries like Pandas and NumPy.
Contribute to architectural and design decisions, ensuring solutions are scalable, resilient, and maintainable.
Participate in code reviews to maintain high standards of quality.
Work with database systems (MongoDB and MySQL) to ensure data integrity and performance.
Collaborate closely with Product Managers to understand requirements.
Guide and mentor junior engineers.