ECS is seeking a Principal Software Engineer to work in our St. Louis, MO office. We are seeking an energetic person to join ECS Federal's elite engineering team supporting one of National Security’s most critical modernization initiative. As a Principal Software Engineer, you'll architect solutions that directly enable warfighters, intelligence professionals, and first responders to make split-second decisions with world-class GEOINT data. Requires final acceptance by the Prime contractor and government customer. Validation of required clearances upon acceptance and approval from a cognizant government contracting officer. After customer indoctrination, the candidate will be submitted for a Counterintelligence Polygraph. This isn't just another federal contract—it's your opportunity to lead transformation efforts that impact global operations daily. You'll work inside a cutting-edge facility, collaborating directly with government technical leads and intelligence analysts to solve problems that don't have textbook answers. Value Proposition Immediate Impact: Your solutions go into production, supporting real-world intelligence operations—not trapped in endless development cycles. Technical Freedom: Lead the architectural direction. We trust senior talent to identify the right tools, frameworks, and approaches without bureaucratic constraints. Innovation Culture: We invest in emerging technologies—AI/ML, automation, advanced analytics—and empower our team to implement them where they add mission value. Elite Collaboration: Work alongside some of the most talented developers, engineers, and scientists in the community. As a Principal Software Engineer, you'll serve as a technical leader and trusted advisor, bridging the gap between complex requirements and impactful technical solutions that will be employed against our nation’s most critical threats: