Junior-Mid Backend Software Engineer

Millennial Software is seeking a Junior - Mid level Backend Software Developer to join our collaborative team supporting National Security. You’ll design, develop, and support scalable APIs and services using a tech stack that power data-driven applications and enable mission-critical decisions. You will focus on backend architecture, data modeling, integrations, performance, and reliability while partnering with frontend engineers, analysts, and users., * 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.

• 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/Google Cloud Platform).
• 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.

Nice to have:

• Experience designing distributed systems (caching, queues, streaming, idempotency, retries, circuit breakers).
• Observability experience: metrics, logging, tracing; familiarity with SLOs/SLIs and incident response practices.
• Experience with data pipelines, ETL/ELT, or search platforms.
• Knowledge of security best practices (threat modeling, secrets management, secure SDLC).
• Experience with performance testing and capacity planning.

Millennial Software is revolutionizing the landscape of security and defense by leveraging our core competencies in software development, automation, DevSecOps, and machine learning.

• 100% company-paid medical, dental, and vision premiums for you and all dependents
• Ability to get increased salary if you don’t need medical/dental/vision
• 100% company-paid disability and life insurance benefits
• 15% 401(k) company contribution
• 30 days of PTO/holidays
• Generous training budget
• Paid Paternal and Maternal Leave
• Business development / growth incentives
• Top notch company swag