Our Mission
Castelion designs, tests, and manufactures next-generation military systems rapidly and at massive scale to deter future wars.
Peace Through Deterrence
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.
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Apprentice Technician
Castelion is seeking a detail-oriented and highly motivated Apprentice Technician to join our manufacturing team. In this role, you will support the design, setup, execution, and documentation of tests on hypersonic missile components and systems during the development phase. You will work closely with design and manufacturing engineering teams to ensure products meet rigorous performance, reliability, and safety standards.- Torrance, CA
- Full time
- In-house
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Avionics Manufacturing Specialist
Castelion is looking for an Avionics Manufacturing Specialist, reporting to the Head of Avionics, to support the development of the systems that will be required for the design and build of long-range hypersonic strike vehicles. This will be a full-time, exempt position located in our El Segundo facility. As an Avionics Manufacturing Specialist, you will work closely with our engineering teams to execute highly technical electrical builds for our research vehicles, assist in advancing designs, and play a critical role in defining and maturing manufacturing, assembly and integration processes.- Torrance, CA
- Full time
- In-house
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Construction Project Manager
As Construction Project Manager, you will be responsible for planning and executing the build-out of new operational and R&D sites for Castelion. You will work closely with internal stakeholders, contractors, architects, and local authorities to ensure our facilities are delivered on time, within budget, and aligned with our mission needs. This role requires a high level of autonomy, field presence, and the ability to thrive in fast-moving, ambiguous environments.- Torrance, CA
- Full time
- In-house
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Cybersecurity Engineer
We’re hiring a Cybersecurity Engineer with experience securing systems in regulated, compliance-heavy environments. If you’re well-versed in frameworks like NIST SP 800-171, CMMC, or ISO 27001, and you know how to turn complex regulatory requirements into practical, enforceable security controls, you’ll feel right at home here.- Torrance, CA
- Full time
- In-house
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Development Test Technician
Castelion is seeking a detail-oriented and highly motivated Development Test Technician to join our manufacturing team. In this role, you will support the design, setup, execution, and documentation of tests on hypersonic missile components and systems during the development phase. You will work closely with design and manufacturing engineering teams to ensure products meet rigorous performance, reliability, and safety standards.- Torrance, CA
- Full time
- In-house
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DevOps Engineer
Castelion is seeking a DevOps Engineer to design, implement, and maintain automated infrastructure, CI/CD pipelines, and cloud-based deployments. The ideal candidate has a strong background in Linux administration, scripting, containerization, and infrastructure automation, along with experience managing Azure cloud services and improving system reliability.- Allen, TX
- Full time
- In-house
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Director of Communications
Were hiring a Director of Communications to lead Castelions storytelling and external communications efforts. This role is responsible for crafting and amplifying our public voice across leading media outlets and key external stakeholders.- Torrance, CA
- Full time
- In-house
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Electrical Technician
We’re looking for a highly skilled, hands-on Electrical Technician to support our engineering team during off-hours, ideally nights or weekends. This is a very part-time role, perfect for someone with a steady hand and a sharp eye who enjoys diving into detailed electrical work.- Allen, TX
- Part-time
- In-house
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Electronics Engineer Intern – Fall 2025 (Avionics)
Castelion is seeking driven and talented Flight Software Engineer Interns for Fall 2025. You’ll help design, build, and test the real-time embedded software that powers our next-generation missile systems, ensuring they operate reliably under extreme conditions. You’ll work alongside experienced flight software, GNC, systems, and hardware engineers to design, implement, test, and debug critical flight code. You won’t be writing throwaway code; your contributions will directly support flight tests, hardware-in-the-loop simulation, and real mission deployments.- Torrance, CA
- Full time
- In-house
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Embedded Software Engineer
As an Embedded Software Engineer you will be at the forefront of creating, developing, and testing the software that drives and simulates our flight systems. Your role involves close collaboration with fellow Castelion engineers across software and hardware domains to implement and debug software across the entire technology stackfrom applications and operating systems to networking, firmware, and simulationensuring complete mission success. We seek intelligent, collaborative, and driven engineers who are passionate about problem-solving and eager to contribute to an extraordinary mission. If you thrive in challenging environments and are excited by the prospect of making a tangible impact, we want to hear from you.- Torrance, CA
- Full time
- In-house
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Embedded Software Engineer Intern – Fall 2025 (Avionics)
Castelion is seeking motivated and talented embedded software engineering interns for 2025. Youll help create the software that drives and simulates our missile systems, from low-level firmware on microcontrollers to high-level integration and testing tools. Youll work alongside experienced embedded, hardware, and flight systems engineers to design, implement, test, and debug real systems in the loop. You wont be writing throwaway code; your contributions will directly support our rapid prototyping and real-world tests.- Torrance, CA
- Full time
- In-house
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Environmental, Health & Safety Engineer
We are seeking an experienced Environmental, Health, and Safety (EH&S) Engineer to join our team in a fast-paced, high-volume manufacturing environment. The ideal candidate will be responsible for ensuring the safety and environmental compliance of our manufacturing processes while driving continuous improvement in health, safety, and environmental performance. This role requires a strong understanding of process safety management, hazard analysis, regulatory compliance, and best practices for industrial safety in the energetics sector.- Torrance, CA
- Full time
- In-house
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Executive Assistant to CEO
As Executive Assistant to the CEO at Castelion, you’ll be the strategic partner who ensures our leadership can focus entirely on developing next-generation defense technologies that protect America and its allies. Working at a defense technology company where precision, security, and flawless execution are paramount, you’ll serve as the operational backbone that enables our CEO to drive the mission of deterring future conflicts through superior long-range strike capabilities. This role offers the unique opportunity to directly support national security objectives while working alongside brilliant engineers and executives in a fast-paced, high-stakes environment where your attention to detail and proactive leadership directly impacts our ability to deliver cutting-edge defense solutions.- Torrance, CA
- Full time
- In-house
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Flight Software Engineer Intern – Fall 2025 (Avionics)
Position Overview: Castelion is seeking driven and talented Flight Software Engineer Interns for 2025. You’ll help design, build, and test the real-time embedded software that powers our next-generation missile systems, ensuring they operate reliably under extreme conditions. You’ll work alongside experienced flight software, GNC, systems, and hardware engineers to design, implement, test, and debug critical flight code. You won’t be writing throwaway code; your contributions will directly support flight tests, hardware-in-the-loop simulation, and real mission deployments.- Torrance, CA
- Full time
- In-house
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Flight Test Director
We are seeking a highly capable Flight Test Director to lead the planning, coordination, and execution of weapon development flight test events. In this role, you will be responsible for ensuring that every test is conducted safely, legally, and in alignment with engineering objectives. You will serve as the central authority for final test readiness, go/no-go decisions, and on-site leadership during test campaigns.- Torrance, CA
- Full time
- In-house
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Flight Test Operations Manager
The Flight Test Operations Manager is the mission enabler for all field test activity. You’ll own the end-to-end logistics and ground operations that ensure every test campaign launches on time, safely, and without friction. From site prep and transportation to emergency planning and team sustainment, you’ll make sure people, equipment, and assets are exactly where they need to be.- Torrance, CA
- Full time
- In-house
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Head of Flight Software
As the Head of Flight Software Engineering, you will lead the development of innovative flight software for Castelion’s advanced missile systems, playing a critical role in achieving our mission of peace through deterrence. This role demands a highly motivated individual with deep expertise in flight software development, a passion for mentoring teams, and a commitment to deliver robust, mission-critical systems. You will oversee all aspects of flight software design, development, integration, and testing, ensuring that Castelion’s cutting-edge systems perform reliably under the most demanding conditions.- Torrance, CA
- Full time
- In-house
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Human Resources Manager
We are looking for a resourceful, hands-on HR Manager to serve as the foundational people leader at Castelion. This is a high-impact role for someone excited to wear multiple hatssupporting hiring, onboarding, compliance, employee relations, culture building, and HR infrastructure. Youll work closely with leadership to ensure our people practices keep pace with our growth and reflect our values of excellence, urgency, and trust. This role is 100% onsite in our Torrance headquarters, embedded in the action alongside engineering and executive teams.- Torrance, CA
- Full time
- In-house
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Lead R&D Technician
Castelion is seeking a detail-oriented and highly motivated Lead R&D Technician to join our manufacturing team. In this role, you will support the design, setup, execution, and documentation of tests on hypersonic missile components and systems during the development phase. You will work closely with design and manufacturing engineering teams to ensure products meet rigorous performance, reliability, and safety standards.- Torrance, CA
- Full time
- In-house
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Senior Aerothermal Engineer
Castelion is seeking an Aero/Thermal Engineer to lead the analysis, design, and optimization of aerodynamic and thermal systems for our hypersonic missile platforms. This role requires expertise in aerodynamics, thermal modeling, and materials to ensure performance and reliability in extreme environments. The ideal candidate will have a hands-on approach and a passion for tackling complex challenges in high-speed flight regimes.- Torrance, CA
- Full time
- In-house
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Senior Avionics Hardware Engineer
As a Senior Avionics Hardware Engineer, you will play a vital role in designing, testing, and optimizing hardware systems for cutting-edge hypersonic missile avionics projects. You will contribute to the development and production of high-quality, reliable hardware components for hypersonic missiles. This role provides a hands-on opportunity to work alongside experienced engineers, gain practical experience, grow your technical skills in a fast-paced and innovative environment, and experience a rapid cadence of test flights where your hardware will be tested in the field.- Torrance, CA
- Full time
- In-house
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Senior Avionics Systems Integration Engineer
Join Castelion and play a pivotal role in advancing the development of next-generation hypersonic missile systems. As an Avionics Systems Engineer, you’ll be part of a cross-disciplinary team responsible for the seamless integration of avionics systems across design, development, testing, and operations. You’ll directly impact mission-critical systems that shape national defense and peace through deterrence.- Torrance, CA
- Full time
- In-house
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Senior Avionics Test Engineer
We are looking for a Senior Avionics Test Engineer to own the validation and performance characterization of our control actuation systems the critical interface between control commands and physical motion on our flight vehicles. You will lead the development of rigorous test infrastructure, design and execute test campaigns, and help define the performance envelope of every actuator that flies.- Torrance, CA
- Full time
- In-house
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Senior Electromechanical Control Systems Engineer
We’re looking for an Electromechanical Control Systems Engineer to lead the development of control actuation systems (CAS) across our missile programs. In this role, you’ll own the design, integration, and validation of servo systems that provide fin control, thrust vector control, and other critical actuation functions. You’ll work across mechanical, electrical, and software domains to create reliable, high-bandwidth systems that can survive the harsh realities of flight.- Torrance, CA
- Full time
- In-house
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Senior Flight Software Engineer
As a Senior Flight Software Engineer, you will play a key role in designing, developing, and testing flight software that powers these advanced systems. You’ll work closely with multidisciplinary teams to deliver high-performance, real-time embedded software that operates reliably under extreme conditions.- Torrance, CA
- Full time
- In-house
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Senior FP&A Analyst
We’re seeking a highly analytical, detail-oriented Senior FP&A Analyst to join our lean, high-impact team. In this role, you will help drive financial visibility and decision-making across a rapidly scaling defense hardware company. You will support planning, forecasting, and performance analysis to enable fast, confident decisions by our leadership and engineering teams.- Torrance, CA
- Full time
- In-house
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Senior GNC Engineer
As a GNC Engineer at Castelion, you will be at the forefront of developing and refining the control systems that guide and control our advanced missile systems. You will be responsible for controlled flight of development vehicles, focusing on aerodynamically efficient flight paths. This position offers the opportunity to work on cutting-edge technology, creating advanced flight control algorithms while validating simulation models through real-world testing. You will collaborate closely with cross-functional engineering teams to deliver accurate flight predictions, drive hardware specification, and conduct successful flight tests.- Torrance, CA
- Full time
- In-house
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Senior Manufacturing Engineer – Mechanisms & Test
Castelion is looking for an expert in the development and maturation of complex mechanical assemblies. This position will be tasked with bringing a mechanical product from conception to full scale production- Torrance, CA
- Full time
- In-house
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Senior Manufacturing Engineer – Motor Case
Castelion is seeking an expert in the manufacture and design of high performance solid rocket motor cases. This role will work closely with design engineering and technician teams to build and execute on testing and validation efforts to keep pace with the research and development timetable of our products. You will be apart of a team responsible for serving as a critical node in implementing feedback from testing and validation efforts, streamlining designs and implementing manufacturing changes to quickly mature our products for flight testing and production. Desire for product and process ownership is a must in this role.- Torrance, CA
- Full time
- In-house
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Senior Materials & Process Engineer
Castelion is seeking a Senior Materials & Process Engineer to develop and validate epoxy bonding processes for our long range, precision strike hypersonic missiles. This role is directly reporting to our Head of Manufacturing and will also work closely with our Materials and Design Engineering teams to test and integrate epoxy bonding processes. A strong understanding of epoxy adhesives and their interactions with other materials is a must as this person will serve as the subject matter expert for the entire organization.- Torrance, CA
- Full time
- In-house
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Senior Mechanical Design Engineer
Castelion is seeking a high output Senior Mechanical Design Engineer with a full stack, Responsible Engineer mindset and experience shipping flight hardware. This person will be responsible for critical flight structures and mechanism design and build efforts for Castelions hypersonic vehicles. The Senior Mechanical Engineer will work closely with a fast-moving team of peers and engineering leadership to ensure mission-critical hardware is delivered on time and meets demanding technical performance. A successful candidate will have significant experience delivering high-performance, mass-constrained hardware in a rapid development environment.- Torrance, CA
- Full time
- In-house
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Senior Mechatronics Engineer
We’re looking for a Senior Mechatronics Engineer to lead the development of control actuation systems (CAS) across our missile programs. In this role, you’ll own the design, integration, and validation of servo systems that provide fin control, thrust vector control, and other critical actuation functions. You’ll work across mechanical, electrical, and software domains to create reliable, high-bandwidth systems that can survive the harsh realities of flight.- Torrance, CA
- Full time
- In-house
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Senior PCB Design Engineer
We are seeking a Senior PCB Design Engineer to lead the design, development, and delivery of smart circuit boards that form the brain of our missile systems. You’ll be responsible for everything from initial architecture through layout, manufacturing, test, and integration. You’ll work closely with electrical, firmware, and mechanical engineers to deliver tightly integrated, high-reliability systems. This role is ideal for someone who has designed and delivered complex smart PCBs – with embedded microcontrollers, high-speed interfaces, and networking components – ideally in constrained or mission-critical environments.- Torrance, CA
- Full time
- In-house
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Senior Propulsion Engineer
The Senior Propulsion Engineer’s primary responsibility is the design of solid rocket motor primary and secondary structures, along with propulsion components, with an emphasis on schedule, affordability and scale.- Torrance, CA
- Full time
- In-house
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Senior Structural Engineer
As Senior Structural Engineer, you will lead structural and site design efforts across our expanding operational footprint. You’ll be responsible for designing and reviewing facilities that house energetic materials, propulsion systems, and advanced R&D efforts. This role requires deep technical expertise, strong field instincts, and experience designing for complex, hazardous environments.- Torrance, CA
- Full time
- In-house
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Senior Warhead Design Engineer
Castelion is designing and building next-generation hypersonic weapon systems that restore stability through credible deterrence. We are seeking a hands-on, mission-driven Ordnance Engineer to lead the design, development, and integration of ordnance systems across our hypersonic vehicles.- Torrance, CA
- Full time
- In-house
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Site Development Lead
We are seeking an experienced and highly motivated Site Development Lead to oversee the planning, design, and execution of site development projects from concept to completion. This leadership role requires a strategic thinker with strong technical knowledge and a proven ability to manage a team while ensuring the project exceeds company goals, is completed on time, and stays within budget. The Site Development Lead will play a key role in coordinating with internal teams, external partners, and stakeholders to ensure the success of critical development projects.- Torrance, CA
- Full time
- In-house
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Software Engineer – Platform Integration
Castelion is seeking a Software Engineer Platform Integration to develop embedded and integration-layer software that enables Castelion’s hypersonic weapon systems to interface with a variety of airborne and ground-based launch platforms. This includes implementing Universal Armament Interface (UAI) protocols for tactical aircraft and supporting Fire Control System (FCS) integration for ground-based launchers. You will contribute to the full lifecycle of integration, from protocol implementation and system communication to simulation, testing, and mission deployment. The ideal candidate is a generalist with strong software fundamentals, experience working across embedded and systems layers, and a drive to build real-world, high-performance systems.- Torrance, CA
- Full time
- In-house
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Software Infrastructure Architect
As a Software Infrastructure Architect you will be at the forefront of architecting, developing, and testing the software that drives data infrastructure. Your role involves close collaboration with fellow Castelion engineers across software and hardware domains to implement and debug data infrastructure software across the entire technology stack from automation of testing to management of lab, test, and flight data ensuring complete mission success. We seek intelligent, collaborative, and driven engineers who are passionate about problem-solving and eager to contribute to an extraordinary mission. If you thrive in challenging environments and are excited by the prospect of making a tangible impact, we want to hear from you.- Torrance, CA
- Full time
- In-house
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Special Projects Lead
Were looking for a Special Projects Leada sharp, execution-oriented generalist who lives at the intersection of strategy, operations, and product. This role reports directly to company leadership and is a unique opportunity to help shape and scale Castelion’s long-term vision from the ground up.- Torrance, CA
- Full time
- In-house
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Test and Quality Engineer
We’re looking for our first Test and Quality Engineer–a hands-on, mission-driven builder who will define and execute our hardware test strategy from the ground up. If you’ve ever dreamed of building a test program, lab, and team from scratch at a high-urgency startup solving national security problems, this is that opportunity.- Torrance, CA
- Full time
- In-house
Castelion News
March 31, 2025 Source: The Economist
Defence tech is blowing up Silicon Valley’s beliefs
In the back of an unmarked office building close to LAX, the main airport of Los Angeles, stands a rack of unarmed hypersonic missiles the size of small drainpipes. On February 6th a camouflaged truck ferried one away to New Mexico for a test launch with the US Air Force. Such activity used to be common in El Segundo, the LA neighbourhood that was once a hub of military spaceflight.
February 13, 2025
Source: WSJ
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.
January 29, 2025
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.
March 11, 2024
Source: Reuters
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.