Software Engineer, AI Systems Simulation

CommonAI Holdings Ltd; Cambridge; Hybrid; GBP 70,000 - 110,000; Full time

Job summary

CommonAI CIC in the UK is seeking engineers to build and connect simulation software for AI infrastructure workloads. You will work on models, components and interfaces to compare design choices across processors, memory, networks and serving strategies against real measurements.

You will join a team that values robust software practices, collaboration with measurement experts, and the use of AI coding agents to support development and testing.

Qualifications

• Strong software engineering skills with evidence of building, debugging and maintaining substantial software.
• Experience in discrete-event simulation, computer architecture or performance modelling, distributed HPC systems, inference runtimes and serving, memory or network modelling.
• Ability to understand unfamiliar code, reason about interfaces and assess reuse/extension viability.
• Collaborative testing approach with adjacent specialists.
• Practical experience using AI coding agents with critical evaluation of outputs.

Responsibilities

• Develop and integrate simulation components capturing AI infrastructure behaviour and interactions.
• Evaluate existing frameworks and extend components via clear interfaces.
• Model system state and resource use to propagate changes correctly.
• Build reproducible simulation scenarios, diagnostics and tests.
• Compare predictions with measurements, refine models and calibrate uncertainty methods.
• Maintain reliable software, documentation and workflows; leverage AI coding agents.
• Bridge simulator components with workload models and datasets for reproducible comparisons.

Skills

Python

C++

Rust

Systems programming

Simulation

Performance modelling

Distributed HPC systems

Inference serving

Code debugging

Tools

vLLM

SGLang

Simulator frameworks

Hardware performance tools

Job description

About CommonAI

CommonAI CIC is a non‑profit organisation built around collaborative engineering and is backed by a mix of UK Government and private funding in order to design, build and deploy innovative AI systems.

Our Scaling Inference Lab (SIL) is developing simulation grounded in real measurements to help the UK invest in promising AI infrastructure. We connect proposed hardware designs to realistic workloads, helping investors and engineers understand their potential, their limitations and the next experiment worth doing.

The Opportunity

Build simulation software that helps engineers and investors explore how AI systems would behave with different processors, memory systems, networks or serving strategies. Your work will help turn models and existing software into a practical framework for comparing design choices against realistic LLM workloads.

You will develop and connect simulation components, making sure that changes in one part of a system have the appropriate consequences elsewhere. This means understanding unfamiliar code, designing clear interfaces and building software whose predictions can be investigated and tested against measurements. We aim to reuse and extend existing frameworks wherever they provide a sound foundation.

We welcome depth in one or more relevant areas, including simulation, systems software, performance modelling and inference serving. Your initial focus will reflect your strengths and the components we choose to build on, with complementary expertise added as the team grows.

What you will do

• Develop and integrate simulation components that capture behaviour and interactions relevant to an AI infrastructure comparison.
• Work with the technical lead and our partners to evaluate existing frameworks and software, extending and connecting useful components through clear interfaces.
• Develop appropriate models of system state and resource use so that changes in one component have the appropriate consequences elsewhere.
• Build reproducible simulation scenarios, diagnostic outputs and tests that expose incorrect assumptions, integration errors and unsupported cases.
• Work with measurement and uncertainty colleagues to compare predictions with evidence, improve models and integrate calibration and uncertainty methods into the simulator.
• Maintain reliable software, documentation and development workflows, using AI coding agents to support implementation and testing.
• An example early project would be to bridge an existing simulator component with our workload models and measurement datasets, producing a reproducible comparison between predicted and measured performance over two systems.
• Strong software engineering skills and evidence of building, debugging and maintaining substantial technical software.
• Experience in one or more of: discrete‑event simulation; computer architecture or performance modelling; distributed/HPC systems; inference runtimes and serving; memory or network modelling; integration of scientific software and heterogeneous components.
• The ability to understand unfamiliar code, reason about interfaces and assess the suitability and maintenance costs of reusing, extending or building software.
• A collaborative approach to testing assumptions and working with specialists in adjacent areas.
• Practical experience using AI coding agents, with the judgement to check their output for correctness and maintainability.

Python, C++, Rust or other relevant systems or scientific programming experience can provide a route into the role. Familiarity with vLLM or SGLang, simulator frameworks, or hardware performance tools would be useful. Depth in a subset of these areas is sufficient; languages and frameworks will follow the engineering needs of the programme.

Why join us

• Help build UK AI capability and improve how investment and compute serve the public good.
• Build a network spanning UK hardware SMEs, major technology companies, venture and public investors, and leading universities.
• Shape a growing team with startup pace and close academic links.
• Use frontier models and coding agents with a substantial tooling budget.

• A collaborative and supportive work environment
• The opportunity to have a high impact in a growing organisation
• Competitive salary package, including pension and benefits
• Professional development opportunities
• Networking opportunities with influential figures from across the tech sector and academia
• A vibrant office environment located a few minutes’ walk away from Cambridge train station

Working with us

Hybrid, with Cambridge attendance agreed individually around collaboration and the work; applicants across the UK are welcome. We are open to permanent employment, part‑time arrangements and consultancy. We would like you to start as soon as practical and can be flexible for the right person.

We particular welcome experienced engineers and can also consider earlier‑career with strong evidence of ability. Relevant postgraduate study is useful, but qualifications are secondary…??

CommonAI CIC is an equal opportunity employer and is committed to creating an inclusive and diverse workplace.