Principal Software Engineer (C++ / C# / Java – Code Refactoring & Modernization)

Smartek21, LLC; United States; Remote; USD 120,000 - 170,000; Full time

Job summary

A leading digital transformation company is seeking a highly experienced Principal Software Engineer to lead code refactoring and modernization initiatives. Candidates should have mastery in C++, C#, and Java, with a focus on performance-critical systems. This remote role requires strong mentorship abilities and a commitment to engineering best practices.

Qualifications

• 10+ years of professional development experience across C++, C#, and Java.
• Advanced mastery of C++11/14/17/20 features.
• Strong knowledge of STL, Boost, and multithreading.

Responsibilities

• Lead large-scale refactoring of legacy systems in C++, C#, and Java.
• Optimize memory usage and performance.
• Mentor developers in advanced refactoring strategies.

Skills

C++ (modern standards)

C#

Java

Refactoring techniques

Performance optimization

Tools

SonarQube

Valgrind

Docker

Kubernetes

Job description

Role Purpose

We are looking for a highly experienced Principal Software Engineer with mastery in C++ (modern standards), C#, and Java to lead large-scale code refactoring and modernization initiatives. This role is for someone who has spent years working in complex, performance-critical systems and can transform legacy, monolithic codebases into clean, modular, high-performance applications.

Core Responsibilities

• Code Refactoring & Modernization: Lead large-scale refactoring of legacy systems in C++, C#, and Java.
• Apply modern language features (C++17/20, C# 10+, Java 11/17) to improve performance, readability, and maintainability.
• Eliminate technical debt, dead code, and anti-patterns through structured refactoring.
• Redesign monolithic applications into modular, service-oriented architectures.
• Performance & Scalability: Optimize memory usage, threading, and concurrency models.
• Profile and fine-tune JVM, CLR, and native C++ runtime performance.
• Apply low-level debugging and optimization techniques in high-performance environments.
• Architecture & Standards: Implement SOLID, clean code, and design pattern practices.
• Introduce coding guidelines, automated static/dynamic analysis tools (SonarQube, Coverity, clang-tidy).
• Ensure all modernized code is testable, maintainable, and CI/CD-ready.
• Collaboration & Mentorship: Partner with architects and technical leads to align modernization with long-term product strategy.
• Mentor developers in advanced refactoring strategies, performance tuning, and clean architecture.
• Conduct deep technical code reviews and enforce engineering best practices.

Required Technical Expertise

• 10+ years of professional development across C++, C#, and Java with extensive cross-language exposure.
• C++: Advanced mastery of C++11/14/17/20 features (smart pointers, lambdas, move semantics, constexpr).
• Strong knowledge of STL, Boost, multithreading, templates, and memory management.
• Hands-on with low-level debugging, profiling tools (Valgrind, Perf, VTune).
• C# / .NET: Deep expertise in .NET 6+, .NET Core, and legacy .NET frameworks.
• Strong understanding of CLR internals, async/await, threading, LINQ, and GC tuning.
• Experience refactoring monolithic .NET applications into modular or microservice-based systems.
• Java: Advanced knowledge of Java 8–17 features (streams, lambdas, records, modules).
• JVM tuning, garbage collection strategies, and threading/concurrency frameworks.
• Experience in Spring / Spring Boot modernization and service decomposition.
• Cross-Cutting Skills: Strong background in design patterns, refactoring techniques, and code smells elimination.
• Expert in unit testing, TDD, and regression-safe refactoring.
• Familiarity with CI/CD pipelines, Git workflows, containerization (Docker, Kubernetes).
• Hands-on with profiling & static analysis tools across all three languages.

This is a remote role for individuals located in the United States of America.

About the Company

SmarTek21, founded in 2006, is an innovative digital transformation leader dedicated to empowering organizations through design-led, data-centric solutions. We believe that exceptional user experiences and intelligent data-driven insights are pivotal in shaping the future of business.

SmarTek21 is committed to fostering a diverse and inclusive environment. We encourage applications from individuals of all backgrounds and experiences.