Principal Software Engineer – C#, .NET Core, Python

FactSet

. Design, develop, and maintain robust backend services and APIs using C# (.NET Core), focusing on high throughput and low latency .

Posted 9/21/2026full-timeUnited StatesLead💰 $165,000 - $215,000 per yearWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates expert-level proficiency in C# and .NET Core for backend system development, alongside strong Python skills for data analysis and scripting. Possesses significant experience in the financial services industry, with a solid understanding of financial instruments and software design patterns.

Highest-signal resume keywords

C# Programming.NET Core DevelopmentPython Data AnalysisRESTful API DevelopmentFinancial Services Expertise

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

C#.NET CorePythonPandasNumPyMongoDBMySQLSoftware Design PatternsData Processing PipelinesAnalytical Scripting

Soft Skills

MentoringCollaborationCode Review

Tools & Technologies

AWSDockerECSServiceStack

Certifications & Qualifications

Bachelor's Degree in Computer ScienceEngineeringMathematics

Industry Keywords

Financial ServicesTrade LifecycleFinancial InstrumentsEquitiesFixed IncomeDerivativesPosition ManagementIBORPortfolio Management System

Tech Stack

Tools & technologies

AWSCloudDockerMongoDBMySQLNumpyPandasPython.NET

About the role

Key responsibilities & impact

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 to ensure solutions are scalable, resilient, and maintainable
Participate in code reviews to maintain high standards of quality
Work with MongoDB and MySQL to ensure data integrity and performance
Work closely with Product Managers to understand requirements
Guide and mentor junior engineers

Requirements

What you’ll need

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
Strong grasp of the trade lifecycle, financial instruments (equities, fixed income, derivatives), and position management concepts
Experience building and consuming RESTful APIs
Solid understanding of software design patterns
Bachelor's degree in Computer Science, Engineering, Mathematics, or a related field
Preferred: Direct experience working on an IBOR or Portfolio Management System
Preferred: Experience with cloud platforms (AWS) and containerisation technologies (Docker/ECS)
Preferred: Experience working with ServiceStack