Senior Software Engineer – Go; Golang

Concept Solutions, LLC (CS) is seeking an experienced Senior Software Engineer – Go (Golang) to support a mission-critical application modernization program for a Department of War (DoW) customer.
This program is focused on simplifying access across a portfolio of production applications through a unified sign-on experience, a shared user interface, and a repeatable approach to integrating applications into a common platform.
In this role, you will help maintain and enhance high-volume, public-facing applications while supporting their integration into a modernized platform. The ideal candidate brings strong backend engineering expertise, hands‑on production experience with Go, and the ability to troubleshoot, maintain, and securely deploy applications in a cloud environment.

• Maintain and support a high-volume, public-facing application built with Go, React/Type Script, and PostgreSQL, containerized on Amazon ECS.
• Hold privileged access to production environments and take ownership of application defects, security patches, and releases in accordance with the customer's release calendar.
• Troubleshoot production issues and implement application fixes to ensure reliability, performance, and availability.
• Maintain application runbooks, operational documentation, and the established sustainment baseline.
• Participate in the Severity 1 on-call rotation and address security vulnerabilities and findings.

• Develop and implement application‑side changes necessary to integrate existing applications with the shared modernization platform.
• Support identity‑provider trust integration, deep‑link routing, redemption endpoints, and data feed access.
• Collaborate with engineering and platform teams to maintain existing application functionality during modernization.
• Follow established change management and privileged‑access procedures when deploying updates to production environments.

• 7+ years of professional backend software engineering experience, including at least 3 years of production Go (Golang) development.
• Strong experience developing and maintaining REST APIs.
• Hands‑on experience with SQL and PostgreSQL databases.
• Experience operating and supporting production applications in a cloud environment.
• Familiarity with formal change control processes and privileged‑access security requirements.
• Ability to troubleshoot complex production issues, implement fixes, and support application releases.

• Experience with React and Type Script.
• Experience with Amazon ECS or Kubernetes.
• Familiarity with AWS Gov Cloud environments.
• Experience integrating applications with identity providers using OIDC or SAML.
• Current favorably adjudicated Tier 5 investigation or active Top Secret clearance, enabling immediate privileged access.

• Location:
  
  Hybrid. Work may be performed at Concept Solutions' Reston, VA headquarters and approved remote locations within the United States, with on‑site work at government facilities in Northern Virginia and Maryland as required.
• Government‑furnished equipment will be used for all access to government environments.
• Schedule:
  
  Full‑time, 40 hours per week, Monday through Friday, with core hours of 9:00 a.m.–3:00 p.m. Eastern. Work follows two‑week Agile sprints, including customer demonstrations each sprint.
• Travel: 0–10%, within the Washington, DC metropolitan area.
• Security Requirement: U.S. citizenship is required. This is a privileged‑access position. Candidates must hold a current favorably adjudicated Tier 5 investigation or Top Secret clearance, or be eligible to obtain one. An active clearance may allow for an earlier start.
• Compensation: $170,000–$180,000…