Job#: 3024075 Job Description: Apex Systems is a world-class technology services business that incorporates industry insights and experience to deliver solutions that fulfill our clients' digital visions.
Apex has an opportunity for a
Senior .NET Developer - Modernization Lead.
If you are interested in this opportunity, please send your updated resume to
Gaby Ortega, Account Manager, at
.
No third parties please.Position: Senior .NET Developer - Modernization LeadLocation: 135 Santilli Highway, Everett, MA 02149Duration: Through 6/30/26 with potential extensionRate: Negotiable Based on ExperienceThis role will support modernization efforts across enterprise C#/.NET applications that power critical operational programs. The Senior .NET Developer - Modernization Lead will drive architectural evolution, refactor legacy systems, strengthen scalability and security, and partner with cross-functional teams to deliver maintainable, high-performing solutions. The position serves as a senior technical leader, guiding design decisions, improving system resiliency, and ensuring long-term stability.
Detailed List of Job Duties and Responsibilities- Lead architectural design, development, and modernization efforts across enterprise C#/.NET applications.
- Provide technical ownership for modernization initiatives including legacy refactoring, cloud-readiness, and system resiliency.
- Translate complex business requirements into scalable, secure technical solutions in collaboration with Business Analysts and Product Owners.
- Establish and enforce architectural standards, coding practices, and design patterns.
- Reduce technical debt and systemic risk through structured remediation plans.
- Coordinate cross-team technical efforts where integrations overlap.
- Mentor developers through design reviews, code reviews, and modernization best practices.
- Design, implement, and govern secure, scalable RESTful APIs and backend services.
- Lead root-cause analysis of high-complexity production issues and implement durable fixes.
- Collaborate with QA and DevOps to strengthen automation, release quality, observability, and deployment reliability.
- Contribute to operational readiness planning, monitoring strategies, and production stability improvements.
- Identify and proactively mitigate architectural risks throughout the delivery lifecycle.
Minimum Qualifications- Bachelor's degree in Computer Science, Information Systems, Engineering, or equivalent experience.
- 7+ years building enterprise applications using C# and .NET (Framework and .NET Core/8/9+ preferred).
- Demonstrated experience leading architectural decision-making within complex or legacy environments.
- Strong expertise in ASP.NET MVC and API-driven architectures.
- Advanced Microsoft SQL Server experience (performance tuning, indexing, query optimization).
- Proven success modernizing legacy systems, refactoring monolithic architectures, and improving maintainability.
- Expertise in secure RESTful API design (JWT, OAuth, claims-based security).
- Experience implementing structured logging, monitoring, and observability in production.
- Strong understanding of dependency injection, middleware, async/await, background services, and distributed processing.
- Working knowledge of modern SPA frameworks (Angular or React).
- Experience mentoring developers and influencing technical standards in Agile environments.
- Proficiency with Git-based source control and CI/CD automation.
- Demonstrated ability to identify systemic risk and create durable, maintainable architecture solutions.
Preferred Qualifications- Experience working in matrixed, cross-agency, or public-sector environments.
- Experience using LLMs and automation tools to enhance engineering productivity.
- Familiarity with cloud platforms and cloud-native architectures.
Additional Requirements- Demonstrable senior-level experience modernizing .NET systems (Core/6+/Cloud).
- Proven ownership, autonomy, and accountability for delivery outcomes.
- Advanced SQL Server performance tuning skills (indexing, execution plans, deadlock analysis).
- Experience with regulated environments (HIPAA, CJIS, FERPA, SOC2) preferred.
- Ability to lead technical design and mentor junior developers.
- Resumes must be kept to 2 pages maximum.
EEO Employer
Apex Systems is an equal opportunity employer. We do not discriminate or allow discrimination on the basis of race, color, religion, creed, sex (including pregnancy, childbirth, breastfeeding, or related medical conditions), age, sexual orientation, gender identity, national origin, ancestry, citizenship, genetic information, registered domestic partner status, marital status, disability, status as a crime victim, protected veteran status, political affiliation, union membership, or any other characteristic protected by law. Apex will consider qualified applicants with criminal histories in a manner consistent with the requirements of applicable law. If you have visited our website in search of information on employment opportunities or to apply for a position, and you require an accommodation in using our website for a search or application, please contact our Employee Services Department at or .
Apex Systems is a world-class IT services company that serves thousands of clients across the globe. When you join Apex, you become part of a team that values innovation, collaboration, and continuous learning. We offer quality career resources, training, certifications, development opportunities, and a comprehensive benefits package. Our commitment to excellence is reflected in many awards, including ClearlyRated's Best of Staffing in Talent Satisfaction in the United States and Great Place to Work in the United Kingdom and Mexico. Apex uses a virtual recruiter as part of the application process. Click for more details.
Apex Benefits Overview: Apex offers a range of supplemental benefits, including medical, dental, vision, life, disability, and other insurance plans that offer an optional layer of financial protection. We offer an ESPP (employee stock purchase program) and a 401K program which allows you to contribute typically within 30 days of starting, with a company match after 12 months of tenure. Apex also offers a HSA (Health Savings Account on the HDHP plan), a SupportLinc Employee Assistance Program (EAP) with up to 8 free counseling sessions, a corporate discount savings program and other discounts. In terms of professional development, Apex hosts an on-demand training program, provides access to certification prep and a library of technical and leadership courses/books/seminars once you have 6+ months of tenure, and certification discounts and other perks to associations that include CompTIA and IIBA. Apex has a dedicated customer service team for our Consultants that can address questions around benefits and other resources, as well as a certified Career Coach. You can access a full list of our benefits, programs, support teams and resources within our 'Welcome Packet' as well, which an Apex team member can provide.
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