Principal Software Engineer Location: Plano, TX or Irvine, CA (Onsite) Type: Full-Time W2 We're looking for a Principal Software Engineer to lead the design and modernization of large-scale enterprise applications while helping drive the adoption of AI-assisted and agentic software engineering. This is a hands-on technical leadership role for someone who enjoys solving complex architectural challenges, building modern cloud-based solutions, and influencing how software is delivered across an organization. What You'll Do • Design and build enterprise applications, APIs, integrations, and distributed systems • Lead development using C#, .NET, SQL Server, Azure, and modern web technologies • Drive modernization of legacy applications and platforms • Define engineering standards, architectural patterns, and best practices • Partner with engineering, DevOps, security, and platform teams • Leverage AI coding assistants and agentic development tools to improve software delivery • Mentor engineers and provide technical leadership across multiple teams What We're Looking For • 10+ years of software engineering experience • Deep expertise in C#/.NET • Strong experience with SQL Server and T-SQL • Experience designing APIs, integrations, and distributed systems • Strong Azure cloud experience • Knowledge of messaging, caching, resiliency, concurrency, and asynchronous processing • Software architecture and design pattern expertise • Experience with AI coding assistants, agentic development platforms, or AI-enabled engineering practices Nice to Have • Python, JavaScript, or TypeScript experience • Experience modernizing large-scale enterprise applications • Prior experience as a Principal Engineer, Staff Engineer, or Architect • Experience in a regulated industry Why Apply? • Influence enterprise technology strategy • Lead AI-assisted and agentic engineering initiatives • Work on large-scale modernization efforts • Partner with highly talented engineering teams • Competitive compensation and career growth opportunities If you're passionate about enterprise-scale engineering and excited about the future of AI-powered software development, we'd love to connect. This posting is for an existing vacancy. Job Type & Location This is a Permanent position based out of Irvine, CA. Pay and Benefits The pay range for this position is $170000.00 - $233000.00/yr. Individual compensation offered for this position within this range will depend on many factors, including qualifications, skills, relevant experience, job knowledge, geographic location, internal equity, and other pertinent job-related factors. Extensive internal growth and professional development opportunities including tuition reimbursement. · Comprehensive benefits package including Medical/Dental/Vision. · Wellness program to support both mental and physical health. · Generous paid time off options to support work-life balance. Job Type & Location This is a Permanent position based out of Irvine, CA. Application Deadline This position is anticipated to close on Nov 6, 2026. Workplace Type This is a fully onsite position in Irvine,CA. About TEKsystems We're partners in transformation. We help clients activate ideas and solutions to take advantage of a new world of opportunity. We are a team of 80,000 strong, working with over 6,000 clients, including 80% of the Fortune 500, across North America, Europe and Asia. As an industry leader in Full-Stack Technology Services, Talent Services, and real-world application, we work with progressive leaders to drive change. That's the power of true partnership. TEKsystems is an Allegis Group company. The company is an equal opportunity employer and will consider all applications without regards to race, sex, age, color, religion, national origin, veteran status, disability, sexual orientation, gender identity, genetic information or any characteristic protected by law. About TEKsystems and TEKsystems Global Services Were a leading provider of business and technology services. We accelerate business transformation for our customers. Our expertise in strategy, design, execution and operations unlocks business value through a range of solutions. Were a team of 80,000 strong, working with over 6,000 customers, including 80% of the Fortune 500 across North America, Europe and Asia, who partner with us for our scale, full-stack capabilities and speed. Were strategic thinkers, hands-on collaborators, helping customers capitalize on change and master the momentum of technology. Were building tomorrow by delivering business outcomes and making positive impacts in our global communities. TEKsystems and TEKsystems Global Services are Allegis Group companies. Learn more at TEKsystems.com. The company is an equal opportunity employer and will consider all applications without regard to race, sex, age, color, religion, national origin, veteran status, disability, sexual orientation, gender identity, genetic information or any characteristic protected by law. San Francisco Fair Chance Ordinance: Pursuant to the San Francisco Fair Chance Ordinance, for all positions located in the city and county of San Francisco, we will consider for employment qualified applicants with arrest and conviction records. Massachusetts Lie Detector: It is unlawful in Massachusetts to require or administer a lie detector test as a condition of employment or continued employment. An employer who violates this law shall be subject to criminal penalties and civil liability. Use of Artificial Intelligence (AI): We may use Artificial Intelligence (AI) to support parts of our hiring process, including sourcing, screening, and evaluating candidates. AI helps assess applications and qualifications, but final decisions are made by our hiring team. By applying, you acknowledge and agree that your application may be reviewed using AI tools.