Senior Back-End Developer (API-Focused)

General information

Description & Requirements

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 maintainability.

• Experience working with at least one RDBMS (SQL Server, PostgreSQL, Oracle, etc.) and with designing APIs around relational data models. 

• Demonstrated experience designing, deploying, and supporting APIs in both cloud-native and legacy-hybrid architectures across Azure or AWS.

Preferred Qualifications:

• Experience supporting Defense Health Agency (DHA), MHS, Veterans Administration (VA), or other federal health agencies.

• Understanding of secure design principles, FedRAMP/IL4/IL5 compliance boundaries, and risk-based mitigation strategies applicable to U.S. Government healthcare environments.

• Experience with GraphQL, gRPC, or other non-REST architectures.

• Certifications such as AWS Certified Solutions Architect (Professional) or Azure Solutions Architect (Expert), or similar.

• Prior experience working with user bases exceeding 10,000, preferably in contexts involving operational healthcare, clinical training, or readiness systems.

Clearance Requirements:

• Must be a U.S. Citizen with the ability to obtain and maintain a Public Trust clearance.

Physical Requirements:

• Office work, typically sedentary with some movement around the office.

• Ability to travel (car or air) and present at conferences or meetings.