Fractile · London or Bristol · Full-time · Hybrid (3 days onsite)
About FractileFractile 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 RoleWe're looking for a Build Systems Engineer to own Bazel at Fractile — designing the tooling that powers every part of what we build, from ML models and kernel drivers to hardware simulation. This is a greenfield role: no legacy, no inherited constraints.
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
- Optimise CI performance across large compute clusters
- Define the developer experience for every engineer at Fractile
- Contribute upstream to Bazel rules we depend on
- No legacy — you're building the Bazel ecosystem from scratch
- 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 software
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
Bonus Points
These aren't requirements, but they'd make you stand out:
- Experience with ML pipelines
- GitHub Actions or similar CI tooling
- Multi-language build systems
- Container-based build environments
- 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.
Ready to apply? Send us your CV and a brief note on what excites you about this role.
