Senior Back-End Developer (API-Focused)

General information

Requisition # R61389 Locations USA-WA-Tacoma Posting Date 06/29/2025 Security Clearance Required None Remote Type Hybrid Time Type Full time

Description & Requirements

Transform the future of federal services with ManTech! Join a vibrant, energetic team committed to enhancing national security and public services through innovative tech. Since 1968, we’ve partnered with Federal Civilian sectors to deliver impactful solutions. Engage in exciting projects in Digital Transformation, Cybersecurity, IT, Data Analytics and more. Ignite your career and drive change. Your journey starts now—innovate and excel with ManTech!

ManTech seeks a motivated, career-focused, and customer-oriented Senior Back-End Developer (API-Focused) to join an on-site team in either: Falls Church, VA, San Antonio, TX, Aurora, CO, or Tacoma, WA.

Responsibilities include but are not limited to:

• Design, implement, and maintain secure, scalable, and well-documented RESTful APIs used across multiple mobile and web applications across the Military Health System (MHS) and its global user base.

• Provide both hands-on programming and mentorship to less experienced developers in API best practices, including service abstraction, versioning, authentication, and observability.

• Collaborate with front-end, mobile, DevSecOps, and shared services engineers to deliver reliable and high-performance back-end services.

• Ensure adherence to modern API design standards (OpenAPI/Swagger, consistent error handling, pagination, etc.) across legacy and greenfield applications.

• Modernize or wrap legacy .NET, SharePoint, Sitecore, and other systems to expose data and business logic security and efficiently.

• Develop and maintain unit, integration, and regression tests for APIs, and automate validation as part of CI/CD pipelines.

• Support DHS’s enterprise modernization by promoting API-first thinking and reusable service patterns across development teams.

• Actively participate in design reviews, code walkthroughs, and production readiness assessments.

Minimum Qualifications:

• 7+ years of progressive experience in software development with at least 2+ years focused on designing and building APIs at scale.

• Bachelor’s degree in Computer Science, Software Engineering, Information Technology, or related discipline.

• Proficiency in one or more server-side languages commonly used for APIs such as C#/.NET Core, Java (Spring Boot), Python (Flask/FastAPI), Node.js, or similar.

• Strong knowledge of secure API authentication and authorization methods (OAuth 2.0, JWT, API keys, mTLS, etc.)

• Experience designing API schemas using OpenAPI/Swagger and documenting APIs for both internal and external consumption.

• Familiarity with modern CI/CD pipelines and containerized deployments (e.g., GitHub Actions, Jenkins, Docker).

• Ability to analyze and refactor legacy APIs or monolithic codebases to improve modularity, performance, and maintainab