Senior Application Developer

SOSi; Fort Belvoir (VA); On-site; USD 140,000 - 155,000; Full time

Job summary

SOSi is seeking a Senior Application Developer to join our team onsite at Fort Belvoir, VA. You will design, develop, integrate, and maintain complex .NET Core applications supporting a government customer. You will mentor junior developers, lead system integration efforts, and ensure secure, scalable delivery while collaborating with cross‑functional teams and staying current with technologies. The role requires TS/SCI-eligible clearance and hands‑on cloud, CI/CD, and API experience.

Qualifications

• Active Top Secret or ability to obtain Top Secret clearance
• 5+ years of technical supervisory experience in software/app development
• Experience with GOTS applications such as ARMIS, AAO, ACOTD, FACTS, MDR, or ADAMS
• Experience with Microsoft SQL and the .NET framework

Responsibilities

• Design, develop, test, and maintain high‑performance software applications.
• Lead architecture and design of application components and integrations.
• Mentor junior developers and support team knowledge sharing.
• Collaborate with product managers, QA, and DevOps to ensure quality and delivery.
• Oversee project operation and documentation across the SDLC

Skills

Leadership

REST APIs

Microservices

Cloud platforms

CI/CD pipelines

SQL/NoSQL

System integration

Mentoring

Communication

Education

Bachelor’s degree or postgraduate degree in engineering, scientific, technical, or business management

Job description

• Compensation: USD 140,000 - USD 155,000 - yearly

Company Description

Founded in 1989, SOSi is among the largest private, founder‑owned technology and services integrators in the defense and government services industry. We deliver tailored solutions, tested leadership, and trusted results to enable national security missions worldwide.

Job Description

Overview:

SOSi is seeking a highly qualified Senior Application Developer to join our team 100% on site in Fort Belvoir, VA, in support of our government customer. In this role, the Senior Application Developer will serve as a technical expert responsible for the design, development, integration, and maintenance of complex software applications. The position requires a strong proficiency in .NET Core and extensive experience supporting the operation, enhancement, and modernization of the ITCD (Information Technology and Compliance Directorate) family of applications. The ideal candidate excels in system integration, collaborates effectively across teams, delivers high‑quality solutions, and provides mentorship to junior developers. This role is best suited for someone who is proactive, detail‑oriented, and committed to building reliable and scalable systems.

• Design, develop, test, and maintain high‑performance software applications.
• Analyze business requirements and translate them into technical specifications.
• Lead the architecture and design of application components and integrations.
• Review code for accuracy, quality, and adherence to best practices.
• Troubleshoot and resolve complex technical issues across the application stack.
• Collaborate with cross‑functional teams, including product managers, QA, and DevOps.
• Contribute to process improvements, automation, and development standards.
• Mentor junior developers and support team knowledge sharing.
• Stay current with emerging technologies and recommend solutions when appropriate.
• Support the project manager in overseeing project operation, planning, and execution.
• Formulate objectives and levels of effort through research and fact‑finding with customer representatives and project managers.
• Be responsible for the software development life cycle from planning to implementation to testing and documenting, to deployment and maintenance.
• Assist the project manager and client in developing a schedule/timeframe for each project to ensure each one is executed efficiently and in a timely manner.
• Create and maintain complete and accurate documentation on all supported applications.
• Oversee technical issues related to the operation, maintenance, and modification of GOTS application.
• Work with customer stakeholders to design or customize software with a focus on optimizing operational efficiency.
• Apply knowledge of hardware and/or software engineering principles.
• Design and/or customize software for client use to optimize operational efficiencies.
• Monitor application performance and perform application changes to optimize performance.
• Analyze and design GOTS applications and systems with a focus on improving functionality and stakeholder usability.
• Provide evaluations and recommendations of GOTS applications and systems to provide solutions to complex technical challenges.
• Follow all applicable agency policies, procedures, and regulations.
• Provide technical guidance to lower‑level developers and engineers.

Qualifications

• Bachelor’s degree or postgraduate degree in engineering, scientific, technical, or business management disciplines from an accredited college or university.
• A minimum of 5 years of technical supervisory experience in an application/software development environment.
• An active in scope Top Secret security clearance, or Secret with the ability to obtain a Top Secret.
• Experience with GOTS applications such as ARMIS, AAO, ACOTD, FACTS, MDR, or ADAMS.
• Experience with Microsoft SQL and the .NET framework.
• Experience with Configuration Management processes including Change Control Boards (CCB).
• Ability to schedule, track, and perform across multiple concurrent projects.
• Must have demonstrated the ability to communicate with a variety of stakeholders in multiple formats.
• Must possess baseline and computing environment certifications for IAT-II IAW DoD 8570.01-M (CCNA‑Security, CySA+, GICSP, GSEC, Security+, CND, or SSCP).
• 5–8+ years of professional experience in software or application development.
• Hands‑on experience with cloud platforms and services (AWS, Azure, or GCP).
• Proficiency with REST APIs, microservices, and application integration patterns.
• Solid understanding of relational and NoSQL databases.
• Experience with CI/CD pipelines, version control systems, and automated testing.
• Strong analytical, problem‑solving, and communication skills.
• Ability to work independently while supporting team goals.

Additional Information

• 100% on government site within Fort Belvoir, VA.
• Normal office conditions.
• Core hours of operation are Monday through Friday, 0600 – 1700.
• No hybrid or remote availability.
• Compensation: $140K - $155K yearly.

Working at SOSi:

• All interested individuals will receive consideration and will not be discriminated against for any reason.