Senior Software Engineer – (C#, .NET)

OneMain Financial; West Valley (WA); On-site; USD 90,000 - 130,000; Full time

Job summary

OneMain Holdings, Inc. is seeking an experienced .NET software engineer to contribute to the architecture and development of enterprise-grade systems, including loan origination and servicing platforms.

You will work on scalable, secure backend services and customer-facing web apps. The role requires 3–5+ years in .NET, strong T-SQL/C#, and hands-on experience with WPF/XAML, WebAPI, and modern frontend connections.

Qualifications

• 3–5+ years of experience developing enterprise-grade applications in .NET.
• Strong skills in T-SQL, C#, and backend service design.
• Understanding of distributed systems and multi-tier architectures.
• Hands-on experience with WPF/XAML, LINQ, MVVM, and WebAPI; exposure to React or Angular is a plus.
• Proficiency in RESTful API design, JSON, and XML integrations.
• Ability to explain technical concepts clearly across teams.
• Experience working in Agile environments with DevOps practices.

Responsibilities

• Contribute to the architecture and development of key systems including Loan Origination Systems, Loan Servicing Systems, and customer-facing applications (e.g., omfauto.com, foursight.com, rateworks.com).
• Ensure scalable, maintainable, and secure software design within assigned projects.
• Implement APIs, middleware services, and integrations with internal and external tools such as Twilio Flex.
• Collaborate with peers through code reviews, design discussions, and pairing sessions.
• Support automation and continuous integration strategies to improve development efficiency and reliability.
• Assist in technical initiatives to modernize legacy systems and improve scalability.
• Participate in troubleshooting and performance tuning to maintain system health.

Skills

.NET development

Backend service design

T-SQL

C#

WebAPI

WPF/XAML

MVVM

LINQ

React or Angular

Agile with DevOps

Mentoring peers

Distributed systems

Multi-tier architectures

Education

Bachelor’s degree in Computer Science, Engineering, or related field

Tools

WPF/XAML

LINQ

MVVM

WebAPI

JSON

XML

Job description

Key Responsibilities

• Contribute to the architecture and development of key systems including Loan Origination Systems, Loan Servicing Systems, and customer-facing applications (e.g., omfauto.com, foursight.com, rateworks.com).
• Ensure scalable, maintainable, and secure software design within assigned projects.
• Implement APIs, middleware services, and integrations with internal and external tools such as Twilio Flex.
• Collaborate with peers through code reviews, design discussions, and pairing sessions.
• Support automation and continuous integration strategies to improve development efficiency and reliability.
• Assist in technical initiatives to modernize legacy systems and improve scalability.
• Participate in troubleshooting and performance tuning to maintain system health.

What Sets You Apart

• 3–5+ years of experience developing enterprise-grade applications in .NET.
• Strong skills in T-SQL, C#, and the .NET Framework with experience in backend service design.
• Understanding of distributed systems and multi-tier application architectures.
• Hands‑on experience with WPF/XAML, LINQ, MVVM, and WebAPI; exposure to React or Angular is a plus.
• Proficiency in RESTful API design, JSON, and XML integrations.
• Ability to explain technical concepts clearly across teams.
• Experience working in Agile environments with DevOps practices.
• Bachelor’s degree in Computer Science, Engineering, or related field.
• Interest in mentoring peers and promoting modern development practices.

OneMain Holdings, Inc. is an Equal Employment Opportunity (EEO) and **Affirmative** Action (AA) employer. Qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender perception or identify, national origin, age, marital status, protected veteran status, or disability status.