DevOps Engineer (Senior) - Bazel Monorepo

DevOps Engineer — Bazel Monorepo Fractile · London or Bristol · Full-time · Hybrid (3 days onsite) About Fractile Fractile is building silicon, systems, and software that will redefine the frontier of AI — running the world's most advanced models at radically higher speed and lower cost. Founded in 2022, our fast-growing team spans hardware and software, working hand in hand to deliver a new class of ML hardware from first principles. If you want to build infrastructure that every engineer in the company depends on, this is the role. The Role We're looking for a Senior DevOps Engineer to own our Bazel monorepo and CI/CD infrastructure at Fractile — designing the tooling, pipelines, and observability that power everything we build, from ML models and kernel drivers to hardware simulation. You'll bring both deep build system expertise and an SRE mindset: owning reliability, debugging CI failures systematically, and giving the engineering organisation clear visibility into how our infrastructure is performing. Your work will become the foundation every engineer at Fractile builds on. That's the scope, and that's the opportunity. What You'll Work On • Design and own Bazel rules and extensions across the stack • Scale our monorepo as we grow across Python, C++, Rust, SystemVerilog, and ML workloads • Create reproducible, multi-language build pipelines • Debug and triage CI pipeline failures across a multi-language monorepo — developing systematic approaches to fault isolation, root cause analysis, and resolution in line with established SRE practices • Optimise CI performance across large compute clusters, applying SLO-driven thinking to build reliability and developer productivity • Build and maintain infrastructure monitoring and observability tooling, giving the engineering organisation clear visibility into build health, pipeline performance, and system reliability • Define alerting thresholds, runbooks, and incident response workflows for build and CI infrastructure • Define the developer experience for every engineer at Fractile • Contribute upstream to Bazel rules we depend on Why This Role Stands Out • Extreme variety — ML, compilers, kernel drivers, simulators, hardware verification • High impact — your work becomes the backbone of the entire engineering organisation • Deep collaboration with Simulation, Runtime, and Hardware teams • Real ownership — you shape how Fractile builds and monitors software What We're Looking For You'll be a strong fit if you have: • 5+ years in software or infrastructure engineering • 3+ years working with build systems • Strong hands-on experience with Bazel • Python scripting and automation skills • Experience with CI/CD for large-scale products, including debugging and resolving pipeline failures at scale • Familiarity with infrastructure monitoring and observability tooling (e.g. Prometheus, Grafana, Datadog, or similar) • Working knowledge of SRE principles — SLOs, alerting design, incident management, and on-call practice Why Fractile • Work at the frontier of AI hardware on genuinely novel engineering problems • A collaborative culture built on curiosity, initiative, and technical depth • Hybrid working: 3 days onsite (London or Bristol), 2 days remote • Modern offices in London and Bristol — choose your base • Competitive salary and equity in a fast-growing company Fractile is committed to building a diverse and inclusive team. We welcome applications from people of all backgrounds and actively encourage candidates from underrepresented groups to apply.