Senior Software Engineer - Machine Learning (Remote US)

About Legion Let’s be real, AI isn’t magic; Legion was built to move beyond AI hype—delivering secure, reliable systems that work alongside the people tackling the world’s most critical challenges. Born from a Department of Defense partnership and trusted by leaders across government and enterprise, Legion embeds intelligence inside complex systems, unlocking data, accelerating human workflows, and strengthening mission-critical systems. We don’t replace workflows—we optimize them, ensuring quality, efficiency, and reliability inside the platforms our partners already use. With world-class collaborators like Palantir, Nvidia, HPE, and Oracle, we’re building intelligent infrastructure that enhances human capability and drives impact at the edge and across a range of enterprises. We’re looking for bold thinkers and doers to join us in shaping the future of AI that’s secure, grounded, and built to work. Staff Applied Machine Learning Engineer (Remote USA) ***US Citizenship or Greencard is required due to US Government contract requirements*** Senior Software Engineer, Machine Learning As a Senior Software Engineer, Machine Learning, you will design, build, and evolve the core AI capabilities that power intelligent experiences across our enterprise AI platform. You will integrate modern foundation models into production systems, develop reusable AI capabilities, and continuously improve their quality, reliability, and performance. Working closely with cross-functional teams, you will transform advances in AI into secure, scalable, and production-ready capabilities that accelerate innovation across the platform. Responsibilities Design, build, and maintain the core AI capabilities that power intelligent experiences across the platform. Develop reusable capabilities for model integration, reasoning, multimodal understanding, structured generation, evaluation, and other foundational AI functionality. Optimize the AI systems that power these capabilities through experimentation, quantitative evaluation, context engineering, and iterative refinement. Apply your production software engineering experience to build backend services, APIs, and distributed AI systems. Partner closely with cross-functional partners to deploy scalable AI services that enable product teams to rapidly build AI-powered experiences. Rapidly prototype emerging AI techniques and translate successful experiments into production-ready platform capabilities. Support production systems by debugging failures and continuously improving latency, reliability, observability, and operational performance. Stay current with advances in AI engineering, foundation models, and applied machine learning, applying them where they create meaningful customer value. Optimize AI systems for performance, latency, reliability, scalability, and cost. Contribute to a collaborative engineering culture focused on ownership and continuous learning. Required Skills and Qualifications Bachelor’s or Master’s degree in Computer Science, Machine Learning, or a related technical field, or equivalent practical experience. 5+ years of experience building production software systems. Strong software engineering skills with experience in Rust, Python, or similar programming languages. Proven ability to build scalable backend services, distributed systems, APIs, or data-intensive applications. Hands-on experience integrating large language models or other foundation models into production applications. Ability to design, evaluate, and improve AI systems through experimentation, quantitative evaluation, and continuous iteration. Familiarity with modern AI engineering patterns such as structured outputs, tool calling, context engineering, multimodal systems, or AI workflows. Strong understanding of software engineering best practices, including testing, observability, reliability, and maintainability. Demonstrated ability to take ownership of technically ambiguous projects from design through production.…