Member of Technical Staff - Security Engineering
Fractile · London / Bristol - Hybrid ·
- Work mode
- Hybrid
- Employment
- Full time
- Category
- Software engineering
- Visa sponsorship
- Yes
- Company size
- 11-50
Fractile · London / Bristol - Hybrid ·
1x · San Carlos, CA
Fluidstack · New York, NY
OpenAI · San Francisco
Anthropic · San Francisco, CA | Seattle, WA
Design and implement security mechanisms for AI hardware control chains, including secure boot, cryptographic key management, and runtime protections across bare metal, RTOS, and Linux.
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.
We build the control chain that powers on, monitors, updates, and protects devices and racks across bare metal, RTOS, and embedded Linux. We also build the communication mechanisms that connect devices to each other and to the host. Security runs through all of it. A chain of trust from the hardware up to the rack management plane: the root of trust each controller boots from, the signed updates that reach the fleet safely, the identity that lets a device prove what it is, the authenticated channels the controllers and devices talk over, and the runtime protections that keep the host Linux kernel and the on-die firmware trustworthy long after boot. These are the layers that let operators rely on the hardware.
You’d be deeply involved in that security across the chain, making it real in software. You’ll work hand in hand with our architecture and hardware teams, bringing the software and system-level view: turning threat models into concrete mechanisms in bare metal, RTOS, and Linux, then designing, prototyping, and validating them. Some of the calls in this model are still open, and you’ll help shape them.
We want engineers who understand security from the inside out. You know how the root of trust, boot chain, key hierarchy, and secure interconnects actually work under the hood, not just how to switch them on. In this role, the security of your software solutions depends entirely on how well you understand the hardware beneath it. Some of the protections we rely on live in silicon, some in software, and part of the skill is knowing which belongs where. We’re looking for people who know both sides well enough to build the mechanisms that close whole classes of bugs by design.
We’re not heavy on levels here! Whether you’d call yourself senior, staff, principal, or lead, what matters is depth of security judgement, system-level experience, and working well with the engineers around you. If you’ve worked deep in the security of real systems and like to get your hands on the code and the systems around it, we’d like to hear from you.
We expect you to know the fundamentals, and to have real, practical experience across several of these:
That’s the core. We get especially curious about your application when you also bring some of the following. Very few candidates tick every box here, and we don’t expect you to:
This is a young company doing hard things, balanced across hardware and software. We’re building the software layer for a whole inference system as it takes shape, so you’ll often be securing systems ahead of the hardware: reasoning about a threat model against a specification first, then a simulator, then early boards. You’ll work with incomplete information and watch it get sharper with every iteration. That takes comfort with ambiguity and a bias for action. If that sounds daunting, this may not be the role. If it sounds like the fun part, we should talk.
Boundaries between areas are soft here. Security touches every layer, so you’ll work across bare metal, RTOS, and Linux, and alongside the architecture and hardware teams as much as the rest of the software team. That breadth is a good part of the job.
You’ll be there for first bring-up, the first secure boot that verifies, the first device that attests itself, the first clean end-to-end run. A piece of what you built will live in silicon and in every rack we ship.
We want a team that reflects the world it’s built for, and we welcome applicants from every background, including those whose path here hasn’t been a straight line. We care that you’re excited by this kind of work, that you bring security rigour, and that you make a team better.
Come build it with us.
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.
Anthropic · San Francisco, United States