SimVentions, Inc. (Glassdoor 4.6), a leading provider of advanced technology solutions to the Department of Defense, is seeking a Mid-Senior Java Developer to join our Information Technology (IT) & Digital Solutions team supporting critical Defense & Aerospace programs. In this role, you will design, develop, and maintain secure, scalable Java-based applications and microservices that enable mission-critical capabilities for our DoD customers. You will work closely with systems engineers, cybersecurity specialists, and other software engineers to translate complex operational requirements into robust, high-quality software solutions. As a Mid-Senior Java Developer, you will lead and contribute to the full software development lifecycle, including requirements analysis, architecture and design, implementation, automated testing, integration, deployment, and sustainment. You will develop back-end services and APIs using modern Java frameworks (such as Spring Boot) and integrate with databases, message queues, and external systems in secure, distributed environments. You will apply secure coding best practices and support compliance with DoD cybersecurity and accreditation standards, collaborating with security engineers to ensure applications meet rigorous security requirements. You will have the opportunity to work in an agile environment, participating in sprint planning, backlog refinement, daily stand-ups, code reviews, and continuous integration/continuous delivery (CI/CD) activities. You will mentor junior developers, contribute to technical design decisions, and help select tools, frameworks, and patterns that improve system performance, reliability, and maintainability. Your work will often involve interfacing with complex defense systems, simulations, and data processing pipelines, requiring strong problem-solving skills and attention to detail. SimVentions fosters a collaborative culture built on innovation, integrity, imagination, and involvement. In this position, you will be encouraged to explore new technologies, propose creative solutions, and continuously refine your craft. You will contribute to a variety of defense technology projects over time, gaining exposure to different mission domains and architectures while working within high-performing, cross-functional teams. The environment emphasizes shared ownership of outcomes, clear communication, and a commitment to delivering excellence for our warfighter customers. This role typically requires professional experience building production-grade Java applications, including hands-on work with RESTful services, relational databases, source control (Git), and automated testing frameworks. Experience in Defense & Aerospace, government contracting, or other highly regulated industries is beneficial, as is familiarity with DevSecOps practices, containerization (Docker, Kubernetes), cloud or on-premise virtualized environments, and continuous integration pipelines. A strong understanding of software engineering fundamentals, including object-oriented design, design patterns, and performance optimization, is essential. Successful candidates will be self-motivated engineers who are comfortable taking ownership of features and systems, collaborating closely with stakeholders, and clearly communicating technical concepts to both technical and non-technical audiences. You should be eager to grow professionally through challenging assignments, training, and mentorship, and you should value working in a supportive environment where your contributions directly impact national defense missions. This Mid-Senior Java Developer position with SimVentions offers the opportunity to combine advanced software engineering with meaningful, mission-driven work in a culture that values both technical excellence and people.