Senior Navigation Software Engineer

Who we are

Theseus is a defense technology company building visual positioning to solve reliability for the next 10 million drones. We’re focused on localization in GPS-denied environments because we believe it is one of the biggest blockers to making autonomous systems reliable in the real world.

Our products are already being used in operational environments today. We’re a small team with high ownership and accountability, and we’re looking for engineers who want to move fast, work against real-world constraints, and see their systems deployed in the field.

The role

We’re seeking a Senior Navigation Software Engineer to lead development of the real-time navigation and state estimation systems at the core of our autonomy stack.

You’ll own the systems that turn onboard sensor data into a continuous, reliable estimate of position and motion without GPS. This role is for someone who can independently drive technical decisions, build robust estimation software, and take systems from concept through deployment on real hardware in demanding environments.

You will:

• Own navigation and state estimation systems end to end, from algorithm design to deployment and field iteration
• Design and improve sensor fusion pipelines that turn onboard sensor data into reliable navigation outputs
• Build estimators that remain robust under real-world failure modes, degraded sensing, and constrained compute
• Define system behavior across initialization, nominal operation, degradation, and recovery, with clear health monitoring
• Drive architecture and technical tradeoffs across the navigation stack, balancing accuracy, robustness, latency, and simplicity
• Partner with autonomy, platform, and flight systems engineers to integrate navigation into the broader product
• Test, debug, and improve system performance in simulation and real flight conditions 

You should have the following

• 4+ years of experience working on robotics navigation, localization, state estimation, sensor fusion, or a closely related problem
• Deep understanding of probabilistic estimation methods, such as Kalman filtering, optimization-based estimation, or visual-inertial navigation
• Strong intuition for inertial sensing, coordinate frames, observability, uncertainty, and real-world failure modes in deployed systems
• Experience building estimation systems that work with real sensor data, not just in simulation or offline research settings
• Strong software engineering skills in C++ and Python
• Demonstrated ability to own technically ambiguous problems and make sound architectural tradeoffs
• Excellent communication and collaboration skills 

Nice to have

• Experience with drones, UAV autonomy, or flight control software such as ArduPilot or PX4
• Background in visual-inertial odometry, SLAM, or production localization systems
• Experience deploying robotics software on edge or embedded compute platforms
• Familiarity with map matching, factor graphs, or multi-sensor fusion architectures
• Experience building evaluation, benchmarking, or validation infrastructure for estimation systems
• Background in aerospace, GNC, autonomous vehicles, or inertial navigation systems