Applications Dev and Test - Software Design Engineer 4

Groupe Kardol; Kennewick (WA); On-site; USD 209,175,000 - 220,636,000; Full time

Job summary

Apex Systems is seeking a Software Design Engineer 4 for onsite work in the Greater Seattle Area, WA. The role focuses on C#/.NET development across frameworks and modern .NET, with extensive cloud, IaC, and DevOps experience.

The candidate will work on large-scale systems, refactor legacy code, and modernize services while ensuring security and reliability. You will design and implement RESTful APIs, participate in cloud deployments, and improve build pipelines and test automation.

Qualifications

• Bachelor's degree in Computer Science, Computer Engineering, or related field required.
• 8+ years of software engineering experience.

Responsibilities

• Design, develop, implement, test, and maintain business and computer applications software or specialized utility programs.
• Modernize services, code base, and infrastructure with focus on business logic.
• Migrate project definitions to new standards and upgrade NuGet packages.
• Improve build pipelines, CI/CD workflows, and ensure code quality and maintainability.
• Prepare software specifications and test plans; code to client specs and create test data.

Skills

C# / .NET Development

Cloud Services

Infrastructure as Code

Build & CI/CD

Testing & Reliability

Security Best Practices

RESTful APIs

DevOps Foundations

Education

Bachelor's degree in CS/CE or related

Tools

Azure DevOps

ARM templates

Bicep

Terraform

Job description

Job #: 3017088

Job Title: Software Design Engineer 4

Duration: Approximately 5 months

Location: Onsite – Greater Seattle Area, WA

Openings: 4

Shortlist Deadline: 1/9/2026

Rate Range: $73–$77/hr

Top 3 Must-Have Skills

• C# / .NET Development (6+ years)
• Strong, hands‑on experience developing production systems using C# across .NET Framework and modern .NET (.NET Core / .NET 6+).
• Proven experience working on large or legacy codebases, including refactoring, modernizing projects, and improving code quality.
• Experience with SDK-style project migrations, NuGet package upgrades, and .NET runtime/framework upgrades.
• Ability to write maintainable, testable code and troubleshoot complex issues in service‑oriented systems.
• Cloud Services (4+ years)
• Hands‑on experience building, deploying, and operating services in a cloud environment.
• Experience developing and maintaining RESTful Web APIs hosted in the cloud.
• Practical experience with cloud environments, including subscriptions, resource groups, and service configuration.
• Familiarity with cloud‑based CI/CD workflows and platform upgrades impacting live services.
• Infrastructure as Code & DevOps Foundations (3+ years)
• Strong experience defining and maintaining infrastructure using Infrastructure as Code (IaC) tools (e.g., ARM templates, Bicep, or Terraform).
• Experience upgrading or migrating build and deployment pipelines (Azure DevOps or equivalent).
• Understanding of infrastructure modernization efforts such as pipeline migrations, environment isolation, and platform compliance requirements.
• Proven ability to improve developer productivity by strengthening build reliability, test pipelines, and automation.

Typical Day in the Role

• Design, develop, implement, test, and maintain business and computer applications software or specialized utility programs.
• Work on modernization of services, code base, and infrastructure, focusing on tasks related to business logic.
• Specific tasks include migrating project definitions to new standards, cleaning up source code warnings, upgrading NuGet packages, and modernizing old services to use updated authentication and authorization methods.
• Additional work may involve build pipeline migrations and infrastructure‑level improvements, with a strong emphasis on C# and cloud experience, covering both .NET Framework and .NET Core.
• Gather and analyze system requirements, document specifications, and develop software solutions to meet client needs.
• Analyze and review enhancement requests and specifications.
• Implement system software and customize to client requirements.
• Prepare detailed software specifications and test plans.
• Code new programs to client’s specifications and create test data for testing.
• Modify existing programs to new standards and conduct unit testing of developed programs.
• Create migration packages for system testing, user testing, and implementation.
• Provide quality assurance reviews.
• Perform post‑implementation validation of software and resolve any bugs found during testing.

Candidate Requirements

• Must have strong technical skills in C#, .NET, cloud services, and Infrastructure as Code.
• Excessive job hopping (e.g., changing jobs every month over the past two years) is considered a red flag.
• Prior experience with large‑scale enterprise systems is preferred.

Best vs. Average Candidate

• Experience splitting or migrating workloads to new repositories or isolated environments to reduce operational overhead.
• Exposure to large or legacy enterprise systems undergoing modernization.
• Experience improving test tooling or developer experience beyond pure feature delivery.
• Experience working in Agile/Scrum teams with two‑week sprints.
• Ability to work independently on scoped technical initiatives while collaborating via code reviews and design discussions.
• Strong communication skills for working with full‑time engineers, other vendors, and partner teams.
• Solid foundation in computer science, with strong competencies in data structures, algorithms, and software design.
• Large systems software design and development experience.
• Experience performing in‑depth troubleshooting and unit testing with both new and legacy production systems.

Core Technical Skills

• C# and .NET: Strong hands‑on experience across .NET Framework and modern .NET (Core / .NET 6+).
• Cloud Application Development: Building and maintaining services in cloud environments, including hosted services and backend components.
• Infrastructure as Code: Hands‑on experience defining and maintaining cloud infrastructure using IaC tools (ARM templates, Bicep, Terraform).
• Build, CI/CD, and Code Hygiene: Improving build pipelines, upgrading workflows, and ensuring code quality and maintainability.
• Testing and Reliability: Improving end‑to‑end test coverage, diagnosing workflow issues, and implementing test automation.
• Security Best Practices: Removing legacy authentication mechanisms and implementing secure identity and access patterns.

Qualifications

• Bachelor’s degree in Computer Science, Computer Engineering, or related field required.
• 8+ years of experience in software engineering.

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 [email protected] or 844-463-6178.

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 an 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.

NYSE: ASGN

4400 Cox Road

Suite 200

Glen Allen, Virginia 23060

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 Benefits Department at [email protected] or 804-523-8228. (Do not submit resumes or solicit consultants to this email address).