Senior Systems Software Engineer

About Fractile Fractile was founded in 2022 on the bet that, eventually, the world’s most capable AI systems would be limited in their impact by the time taken to produce useful outputs. We bet everything on the logical conclusion: that the only way to truly unlock this latent value, to make speed viable at scale, was to radically re-invent the hardware that we run our frontier AI models on. Ever since, we have been building chips and systems that tackle this problem: how to efficiently generate output at thousands of tokens per second, while handling the complexity and capacity challenges of operating large models at very long contexts. The workloads that push to the limits of the current frontier are already transformational; it is the technical and economic limits on inference speed that are constraining progress. The defining work of the 21st century will be marked by the engine of inference delivering immense and diffuse chains of intellectual inquiry, in drug discovery, in software engineering, in materials discovery, in any field where progress is driven by deep reasoning and intelligence to resolve complex problems. The Role We build the control chain that powers on, monitors, updates, and protects devices and racks across bare metal, RTOS, and embedded Linux. It’s production-critical software that keeps racks stable, updates safe, and hardware secure. It’s a critical layer in turning a tokens per second benchmark into a tokens per month system, turning great silicon into reliable output at rack scale. You’ll be there for the first racks coming to life and rollout days where update safety matters. Your work makes the difference between a bad failure and a clean recovery path. This is the work that makes the system something operators can trust. What you’ll do • Develop firmware and services for management controllers at every level: rack management, BMC, and board/device controllers (RTOS and bare metal) • Build systems software for board and rack management, from early bring-up through to production deployment • Implement the critical flows that keep fleets healthy: power-on and provisioning, monitoring/telemetry, updates, recovery, and security • Integrate with the wider host/device stack (drivers and runtime libraries) so the system works end-to-end • Work closely with hardware and device software teams to define reliable interfaces, validate behaviour, and debug boundary issues What we’re looking for • Proven experience shipping production-critical, reliable embedded systems across two or more of: bare metal, RTOS, embedded Linux (or deep expertise in one with clear ability to ramp the others) • Strong C and/or Rust, and excellent engineering judgement around safety, testing, debugging, and failure modes • A reliability-first mindset: you design for observability, diagnosability, and recovery paths that are predictable and testable • Comfortable working close to the hardware/software boundary (bootloaders/BSP/kernel-adjacent work) and collaborating tightly with HW, driver, and runtime teams • Collaborative and high-ownership. You communicate clearly, move fast, and enjoy working through hard problems with others • Computer Science, Electronic Engineering, Maths, Physics, or related degree and 3+ years of industry experience Nice to have • Embedded platform / systems firmware experience (board management, BMC-style stacks, rack controllers) • OpenBMC experience and/or embedded Linux image build/customisation experience • Zephyr (or similar RTOS) experience • Security-minded, with practical instincts around secure boot, signed updates, device identity, and designing systems that fail safe and recover cleanly (direct experience in some areas is a plus) • Kernel device work (drivers, device tree, bring-up, perf/trace) • Hardware bring-up experience, including lab tools (logic analysers, oscilloscopes, waveform viewers) • RISC-V familiarity • Experience with GPUs or ML accelerators If you want to build the control software that keeps rack-scale systems stable, safe, and secure for next-gen AI, come build it together. What We Offer • Competitive salary: A competitive salary reflective of your experience and the specialist nature of the role. • Equity & Ownership: meaningful equity so everyone shares in the value creation • Benefits: Private Medical, Dental and Vision, Contributory Pension, 25 Days holiday plus bank holidays and Life/Critical Illness Insurance. • Diverse & fun office: we believe the hardest problems get solved by the broadest range of minds. We are committed to Equal Employment Opportunity through attracting and retaining a diverse team and building an inclusive environment. Fractile is seeking to increase the clock speed of global progress, one chip at a time. We’ve recently raised $220M from investors including Founders Fund and Accel and our most important work lies ahead. Join us! Export controls Our work involves technologies subject to UK, US and other international export control regulations. Certain roles may require additional eligibility checks to ensure compliance with applicable law. We'll be transparent about this throughout the hiring process.