Modelling Engineer

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.

About the Software organisation at Fractile

PerfSim sits within the Software organisation at Fractile, which is responsible for developing a full software stack for our groundbreaking AI inference systems. That's everything from ML compilers, device drivers and systems firmware, application level runtime and ecosystem integrations, ML and compute libraries, great developer tooling and a full portfolio of simulators, through to datacenter scale workload deployment solutions. At Fractile, we know that a fantastic software stack is a critical and central part of any AI inference solution and it sits at the heart of everything we're doing.

About the team and role

To build hardware that doesn't yet exist, you first have to model it — with precision, depth, and an eye for the trade-offs that matter. At Fractile, high-fidelity pre-silicon models shape our architecture, performance, and product design long before hardware exists. The Simulation team includes C++ and SystemC specialists, verification and validation engineers, system architects, and embedded engineers. This is not a support function — it is the group that defines how Fractile's hardware behaves.

As a Modelling Engineer you will develop the pre-silicon models of Fractile's AI acceleration hardware, enabling architectural exploration and definition, functional modelling, performance modelling and bottleneck analysis, and early software development on virtual platforms. You will work closely with hardware, software, and ML teams in a true hardware–software co-design loop.

About you

You have a genuine curiosity for hard problems and the depth to operate across architecture, performance, and functional correctness. You understand that the models you build will shape the architecture of Fractile's accelerator, determine performance trade-offs, enable early runtime and compiler development, unblock software teams months before silicon exists, and reduce risk across the entire product lifecycle. You take that responsibility seriously and bring the rigour it demands.

Key Requirements

• Experience in pre-silicon modelling of complex semiconductor IP

• SystemC or equivalent modelling frameworks

• C++ for high-performance simulation

• Performance modelling and architectural analysis

• Verification and functional modelling

Nice to Have

• Experience with ML workloads or ML accelerator architectures

• Prior startup or small-team experience

• 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.