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.
Skills Required
- 5 years experience in Software Engineering or Infrastructure Engineering
- 3 years of experience with build tools
- Experience building and maintaining advanced CI/CD pipelines for large-scale products
- Proficiency with Bazel
- Scripting and automation skills in Python
- A degree in Computer Science, Engineering, or a related field (or equivalent experience)
What We Do
Fractile is developing AI chips designed for efficient AI model inference, aiming to radically improve the speed and cost of running frontier AI models by eliminating memory bottlenecks.
