Infrastructure Software Engineering – Platform & Build in London

Location: London

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. Fractile is seeking to increase the clock speed of global progress, one chip at a time. We’ve recently raised $220M from Founders Fund and Accel and the most important work lies ahead. Come and join the mission!

The Role

As an Infrastructure Platform Engineer you will be a core part of our technical team working alongside the hardware, software and research teams to solve cutting-edge problems in AI hardware, ranging from verification to simulation, alongside the best of the best (DeepMind, Apple, Meta…).

About the Software organisation at Fractile

Infrastructure 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

The Infrastructure team is responsible for the core platform and systems at Fractile. We build, scale, and optimize the mission-critical systems that power our entire engineering org, including our multi-language Bazel monorepo and CI pipelines. From hardware design and verification to kernel development and ML compilers, we enable all Fractile engineers to ship fast and reliably. The team brings both deep build system expertise and an SRE mindset: reliability, build performance, debugging CI failures systematically, and giving the engineering organisation clear visibility into how our infrastructure is performing.

As an Infrastructure Platform Engineer, you will:

• Own the CI infrastructure end-to-end: create, maintain and debug reproducible multi-language CI pipelines, and optimize CI performance across large compute clusters.
• Build and maintain infrastructure observability, alerting, runbooks, and incident response workflows for Fractile's infrastructure.
• Scale and maintain Fractile's Bazel monorepo as we continue growing across Python, C++, Rust, SystemVerilog, and ML workloads.
• Shape the infrastructure and platform experience for every engineer at Fractile.

About you

You bring deep infrastructure and build systems expertise alongside an SRE mindset. You are systematic in how you approach fault isolation and root cause analysis, and you apply metrics-driven thinking to build reliability and developer productivity. You thrive on variety (ML, compilers, kernel drivers, simulators, hardware verification) and you understand that your work becomes the foundation every engineer at Fractile builds on. You take that responsibility seriously.

Key Requirements

• 5+ years in software, platform, or infrastructure engineering
• 5+ years hands-on experience working with CI/CD for large-scale products, including monitoring, debugging performance and resolving pipeline failures at scale
• 3+ years working with build systems, preferably modern cross-language build systems with an emphasis on correctness, high performance and extensibility, such as Bazel, Buck, Pants, Please, etc.
• Experience with infrastructure as code (Terraform, OpenTofu, or Pulumi)
• Experience with monitoring and observability tooling (Prometheus, Grafana, or similar)
• Working knowledge and practice of DevOps / SRE principles: SLOs, alerting design, incident management, and on-call practice
• Strong proficiency in at least one systems or scripting language used for tooling (Python preferred; Go or Rust also relevant), with a track record of shipping well-tested, maintainable developer tooling that other engineers rely on: CLIs, CI integrations, build and release automation

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

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.