Backend Engineer TS/SCI with Poly — Secure APIs & Scale

Millennial Software; Chantilly (VA); On-site; USD 95,000 - 180,000; Full time

Benefits offered by this job

Medical premiums for employee & depend

Dental premiums for employee & depend

Vision premiums for employee & depend

Disability & life insurance

401(k) 15% company contribution

PTO & holidays 30 days

Paid parental leave

Training budget

Company swag

Job summary

Millennial Software is seeking a Junior - Mid level Backend Software Developer to join our team supporting National Security. You’ll design, develop, and support scalable APIs and services using a tech stack that powers data-driven applications and enable mission-critical decisions.

You will focus on backend architecture, data modeling, integrations, performance, and reliability. The ideal candidate is passionate about the full lifecycle—design, coding, testing, deployment, and sustainment—and

Qualifications

• Demonstrated experience building and operating production backend services and APIs.
• Proficiency in at least one backend language (e.g., Python, Java, Go, C#, Node.js) and common frameworks.
• Strong understanding of API design, authentication/authorization concepts, and service reliability.
• Experience with relational and/or NoSQL databases, query optimization, and schema/data modeling.
• Experience with messaging and queuing platforms such as Kafka, RabbitMQ, or similar.
• Familiarity with testing strategies and CI workflows; comfort with debugging and incident triage.
• Ability to collaborate cross-functionally and communicate technical decisions clearly.
• Experience creating and maintaining Docker containers, Helm charts, orchestration platforms such as Kubernetes clusters, and using cloud infrastructure services (AWS/Azure/GCP).
• Bachelor’s degree in a related field or equivalent practical experience.
• At least 2-10 years performing backend software engineering.
• Active TS/SCI clearance.
• Ability to work on-site at one of the following locations - Virginia: Fairfax, Chantilly, McLean, Sterling, or Colorado: Colorado Springs.

Responsibilities

• Design, implement, and maintain backend services, APIs, and integrations that support product features.
• Develop data models and persistence layers; ensure data quality, integrity, and performance.
• Build reliable service-to-service communication and integration patterns (REST/GraphQL, messaging, streaming).
• Apply secure coding practices and ensure appropriate authentication/authorization patterns.
• Create and maintain automated tests (unit/integration) and participate in peer code reviews.
• Diagnose and resolve production issues; improve reliability through monitoring, alerting, and runbooks.
• Collaborate with frontend engineers and other stakeholders to define contracts and support end-to-end delivery.
• Identify bottlenecks and drive performance improvements (latency, throughput, resource utilization).
• Produce technical documentation for systems, APIs, and operational procedures.

Skills

Backend development

Programming languages

API design

Databases

Messaging systems

CI/CD

Docker & Kubernetes

Cloud platforms

Team collaboration

TS/SCI clearance

Education

Bachelor's degree or higher

Tools

Docker

Kubernetes

Git

CI/CD tooling

Job description

Millennial Software is seeking a Junior - Mid level Backend Software Developer to join our team supporting National Security. You’ll design, develop, and support scalable APIs and services using a tech stack that powers data-driven applications and enable mission-critical decisions.

You will focus on backend architecture, data modeling, integrations, performance, and reliability. The ideal candidate is passionate about the full lifecycle—design, coding, testing, deployment, and sustainment—and