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.