Staff Software Engineer

Senior Principal / Staff Engineer — Watchtower Labs

In-person only - Bellevue, WA

U.S. Citizenship required (DoD Clearance preferable)

This is not a “backend engineer” role in the usual sense.

This is a seat for a creator: someone who can take an undefined, high-stakes problem and produce a working system that survives reality: load, edge cases, adversarial conditions, security constraints, and changing requirements.

If you need a perfect spec, gentle timelines, and a clean handoff chain, do not apply. If you want to build what doesn’t exist yet and you’re wired for hard problems, read on. Instruction for applying below.

The mission

We build simulation and autonomy infrastructure that supports critical outcomes for US defense. The work is demanding because the domain is demanding: uncertainty, complexity, speed, and correctness all at once.

The work

You will own core systems behind a multi-agent simulation engine:

• Design primitives: orchestration, state, time, execution models, and scaling strategy
• Build and run distributed services that must be reliable, observable, and secure
• Drive performance until it hurts: profiling, contention, memory, throughput, p99s
• Build infrastructure that behaves under stress, not just in a demo
• Make calls with incomplete info and be right often enough to move fast
• Lead by doing: you’ll ship critical pieces yourself and pull others up with you

The bar

We’re looking for rare engineering traits:

• Architect-level judgment: you see failure modes before they happen
• Relentless ownership: you fix what you touch, and you touch what matters
• Grit: you don’t get fragile when the system fights back
• Curiosity: you chase first principles, not vibes
• Competitive excellence: you care about being great, not merely “done”

Proven track record of tangibly contributing to complex systems.

What you should bring

• Deep experience building real systems in production (distributed, performance-sensitive, mission-critical)
• Comfort working across C#/.NET Core, Linux, Python (or equivalent mastery + fast learning)
• Strong mental model of systems: concurrency, networking, data integrity, deploy/release, observability
• Ability to thrive in-person with a high-output team and high standards

What you will get

• The kind of problems that force you to level up
• A team that values builders and moves fast without lying to itself
• Work with real consequences and real pride when it ships