Hardware Designed for Production at Scale
Castelion delivers the capabilities America needs to preserve peace through credible, non-nuclear deterrence. We build at the scale national security demands – optimizing every system for cost, manufacturability, and rapid deployment.
Hardware Rich.
Rapid Test and Iteration.
Designed for Scaled Manufacturing.
Affordable Hypersonic Weapons, Built Fast
At Castelion, speed and cost aren’t tradeoffs—they’re requirements. We vertically integrate core technologies to move faster, reduce risk, and control cost at scale. Every system is designed for manufacturability from day one, enabling rapid iteration and high-volume production. In today’s threat environment, speed matters. Affordability matters. We’re building with both.
Protecting Democracy
Our mission is rooted in the belief that freedom must be actively protected—through technological strength, strategic clarity, and national resolve. By restoring America’s ability to out-innovate and out-produce its rivals, we help ensure that the free world remains secure for generations to come.
Hardware Rich
Rapid Testing
Iterative Design
America Needs You!
Ready to get your hands on real hardware, own critical projects, and make your work count? Explore our open roles and help shape the future of defense.
Featured Positions
Choose your next adventure with Castelion.
Castelion News
Startup Castelion Raises $100 Million for Hypersonic Strike Weapons
Silicon Valley’s enthusiasm for superfast weapons has picked up speed, with defense-tech startup Castelion raising $100 million through debt and equity to build hypersonic missile systems.
Castelion Announces Series A Funding
Castelion is excited to announce a $100M capital raise. This includes a $70M Series A, led by Lightspeed Venture Partners with participation from a16z, Lavrock Ventures, Cantos, First In, BlueYard Capital, and Interlagos, and $30M in Venture Debt financing provided by Silicon Valley Bank, with final close expected in February. With this funding we will further accelerate test cycles, scale our mass production facilities, and execute a capability demonstration of our first hypersonic weapon. These efforts will move us faster and closer to regaining a decisive advantage and thereby creating credible deterrence.
Hypersonic weapon startup Castelion has first prototype missile test
Castelion, a startup trying to build a hypersonic weapon for the Pentagon, tested its system for the first time, it told Reuters on Monday, as a growing group of small hypersonic arms makers challenge large defense contractors with less expensive, rapidly produced products.