Senior .NET Developer

We are looking for a highly skilled outsourced development team to support and enhance a large, business-critical application built on .NET Framework 4.8. The system relies on numerous third-party libraries—some of which require updates or replacements to ensure security, stability, and long-term maintainability. The application also uses ServiceStack for API delivery and integrates with a high-volume SQL Server backend.

Requirements

Overview

We are looking for a highly experienced .NET Lead to join our team and provide technical leadership for a large, business-critical platform built on .NET Framework 4.8. Our application relies on numerous third-party libraries and exposes APIs using ServiceStack. We are entering a strategic phase focused on performance optimization, modernization, technical improvements, and ongoing support.

This role requires deep technical expertise, strong architectural thinking, and hands-on experience maintaining and scaling enterprise applications.

Key Responsibilities

• Lead maintenance and enhancement of a large, mission-critical .NET application.
• Drive performance optimization efforts across multiple functional areas.
• Refactor, upgrade, or replace outdated or vulnerable third-party libraries to improve security and maintainability.
• Contribute to modernization initiatives, helping steer the long-term technical evolution of the system.
• Support and enhance a large SQL Server backend, including:
• Tables containing billions of rows
• Query optimization
• Ensuring stability and high performance under heavy load
• Collaborate closely with internal technical leadership to:
• Address defects
• Implement incremental improvements
• Ensure architectural alignment and code quality
• Provide mentorship and guidance to developers within the team.

Requirements

• 7+ years of professional experience with .NET Framework (including 4.8).
• Strong expertise in C#, object-oriented design, and enterprise application development.
• Hands-on experience working with ServiceStack or similar API frameworks.
• Proven track record optimizing SQL Server queries and working with extremely large datasets.
• Experience refactoring legacy code and modernizing existing systems.
• Ability to take ownership of complex technical challenges and drive solutions.
• Strong communication, documentation, and collaboration skills.

Nice to Have

• Experience transitioning legacy applications toward modern .NET versions (.NET 6/7/8+).
• Familiarity with CI/CD pipelines, automated testing, and DevOps practices.
• Background leading or mentoring development teams.

Benefits

• Chance to take charge and shape a vital application critical to the business.
• Partnership with a skilled team of technical leaders.
• Long-term involvement in meaningful and challenging engineering projects.
• Remote work flexibility.