Compensation reflecting your skills and experience.

About Us

Artificial intelligence scaled on a bet - that bigger models, more identical chips, and more data would keep delivering. As problems become more complex and the requirements of intelligence more diverse, that bet is breaking down.

We believe that the next era of AI belongs to heterogeneous intelligence: diverse models on diverse chips, each with distinct strengths, working together into something greater than the sum of their parts. Novel accelerators are emerging from every direction, but no infrastructure exists to bring them together. We are building it.

Callosum is the Intelligent Systems company. We believe intelligence comes from the system, not the model - where chips and models co-evolve to unlock discoveries unreachable under the current paradigm.

We are scientists and engineers solving what others consider impossible. If you thrive on hard problems, are passionate and energised by the scale of the challenge, we'd love to hear from you.

About the Role

As the Systems Tooling Engineer, you will be responsible for building the operational layer that connects experimentation to deployment across Callosum's heterogeneous compute stack. You will prototype and validate ideas, and evolve that work into performant, low-level systems in Rust/C++ as it matures.

The tooling you build will span every layer of the stack, letting us exploit new compute environments at speed. You will operate across the full development lifecycle - from experiment harnesses and profiling utilities, to production-grade scheduling and observability infrastructure.

The role has growth potential toward technical leadership in platform engineering, performance architecture and systems toolchain design, and involves close collaboration with systems and infrastructure engineering teams.

Your Responsibilities

• Fully own the design and development of operational tooling across the heterogeneous compute stack, from early prototype to production-grade system

• Rapidly prototype and validate ideas in Python, then evolve performance-critical components into Rust or C++

• Instrument, profile, and benchmark tooling to identify and eliminate performance bottlenecks across the stack

• Establish and maintain CI/CD pipelines, performance regression tracking, and observability infrastructure

Skills & Qualifications

• Master’s or equivalent practical experience in a relevant technical field.

• Strong proficiency in Python for experimentation and rapid prototyping

• Strong foundation in performance-aware systems design, including scalable algorithms, memory layout, concurrency, and asynchronous patterns

• Familiarity with CI/CD and automated testing practices; familiarity with performance regression tracking, and observability/profiling-driven validation

Nice to have

• Experience with Rust/C++ in a production setting

• Exposure to heterogeneous compute environments or HPC workloads

• Familiarity with distributed systems concepts - scheduling, data-plane tooling, or resource allocation

What We Offer

• Competitive Salary: £101,000 - £192,000, determined by skills and experience.

• Equity & Ownership

• Medical and dental healthcare

• We offer Visa sponsorship and relocation benefits to hire the best in the world

• We work in person at our London office. You'll have the tools, space and setup to do your best work, and if you have specific needs, just tell us

We're committed to building an inclusive workplace where everyone feels welcome, and believe in equal opportunities for all.

Compensation Range: £101K - £192K