Senior Software Engineer/Engineer II

About the Role

As a Senior Software Engineer at 4C, you'll lead technical design and development within an agile team, own features and components end to end, and take on the hardest problems we have. This is a hands-on senior role: you'll write production code, drive design decisions, mentor other engineers, and work directly with DoD customers to understand what they need and explain the tradeoffs in how we build it. You'll also help shape how we integrate LLM-based and agentic capabilities into our simulation and training solutions, with an emphasis on reliability, evaluation, and predictable behavior

Key Responsibilities

• Lead the design and development of software systems across military, industrial, and commercial domains

• Own features and components from technical design through delivery and support

• Drive technical design decisions and help break down and estimate complex work

• Design and integrate LLM-based and agentic capabilities, with attention to reliability, evaluation, and safe, predictable behavior

• Troubleshoot and resolve complex issues across the codebase and in production

• Establish and maintain testing and quality standards, including automated testing

• Lead peer code reviews and mentor more junior engineers

• Drive improvements to team processes, practices, and technical standards

About You

You bring deep technical judgment and take ownership of outcomes, not just tasks. You're a strong communicator who can align a team around a design and explain technical tradeoffs to both engineers and customers. You have a solution-oriented mindset and thrive on hard, ambiguous problems. You raise the quality of the people and systems around you, and you stay current as technology — including agentic AI — evolves quickly.

What You Bring

• 5+ years building, deploying, and supporting production web applications

• Strong Java backend experience (Spring Framework and/or Jakarta EE — JPA, JAX-RS, WebSocket, servlet containers)

• Strong experience with a modern frontend framework; Angular preferred (TypeScript, RxJS, NgRx)

• REST/API design and a solid grounding in distributed systems

• Hands-on CI/CD and containerized deployment in production (GitLab CI, Docker, Kubernetes or similar)

• Automated testing discipline (JUnit, Playwright or similar)

• Deep knowledge of core computer science and software engineering fundamentals

• Clear communicator who can align a team around a design and explain tradeoffs to engineers and customers

• Demonstrated ability to mentor engineers

Nice to Have

• Experience building production LLM-based or agentic systems (tool-calling, orchestration, retrieval, evaluation) and fluency with AI-assisted development tools

• Event-driven and message-based architectures (Kafka, AMQP, JMS)

• Distributed simulation integration using DIS or HLA (IEEE 1516), or comparable real-time, event-driven work

• gRPC/Protobuf, OpenAPI

• Prior work in defense, training and simulation, or other mission-critical domains

Qualifications

• Bachelor's degree in Computer Science or a related field (or equivalent experience)

• U.S. citizen with the ability to obtain a Secret security clearance, active clearance a plus

• Ability to travel internationally to work with our clients and teams

What We Value

• Experience building production LLM-based and agentic systems (tool-calling, orchestration, retrieval, evaluation), and fluency with AI-assisted development tooling

• Deep knowledge of event-driven and message-based architectures and technologies such as AMQP, Kafka, and JMS

• Hands-on experience integrating distributed simulation systems using DIS (Distributed Interactive Simulation) and HLA (High Level Architecture / IEEE 1516)

• Experience in defense, training and simulation, or other mission-critical domains