Inference Engine Development - Member of Technical Staff
Possible
Sponsorship likelihood
This employer issued few or no visas recently
£54,700
Going rate
Skilled Worker going rate
This role likely qualifies for a Skilled Worker visa
SOC 2134 (85% match) is an eligible occupation, with a going rate of £54,700, and CALLOSUM LTD is a licensed sponsor. That is our reading of the rules. Whether they issue a Certificate of Sponsorship is still their call.
This could also be SOC 2133 (IT business analysts, architects and systems designers, Infrastructure/architecture focus on heterogeneous compute systems) or SOC 2129 (Engineering professionals not elsewhere classified, Engineering professional role on inference engines). We read the code off the advert, so it is our best guess, not the employer's.
New graduate or PhD holder? Pick one of the lower rates.
What each route needs for this job
| Occupation code | New entrant 70% of going rate | STEM PhD 80% of going rate | Relevant PhD 90% of going rate | Standard rate 100% of going rate |
|---|---|---|---|---|
2134 Programmers and software development professionals Most likely code | £38,300 Clears | £43,700 Clears | £49,200 Clears | £54,700 Clears |
2133 IT business analysts, architects and systems designers Also possible | £38,400 Clears | £43,900 Clears | £49,400 Clears | £54,900 Clears |
2129 Engineering professionals not elsewhere classified Also possible | £33,400 Clears | £36,900 Clears | £41,500 Clears | £46,100 Clears |
We use the lowest threshold across the plausible codes. Likelihood is Possible at most when the pay clears only a lower rate, or only under a less likely code. A mark is for the top of the advertised pay. How the Home Office picks the code
About the role
About Us
We’re living through a Cambrian explosion of intelligence: new models and new chips, each specialised for different tasks, are arriving all at once. The result is a new era for AI, one of radical heterogeneity.
Callosum is the Intelligent Systems Company. We believe the next generation of AI won't be defined by any single model or chip, but by intelligent systems in which hardware and intelligence co-evolve. We are building the infrastructure that unifies heterogeneous compute across the full stack. This opens a new axis of scaling intelligence: a dynamic system that tailors itself to what each workload actually needs, whether that's speed, cost, precision, or whatever unit comes next.
The last era scaled on a different bet: one bigger model, more of the same chip, more data. That bet is running into structural limits. Frontier models offer extraordinary capability at unsustainable cost, one that today's monolithic infrastructure was never designed to serve.
Our founding principle is that intelligence comes from many specialised systems working together, not from any single component. We build the software orchestration layer that co-evolves models, workflows and silicon into one system, delivering inference tailored to every workload, and demonstrating orders-of-magnitude leaps in capability and cost.
Because our software spans the full stack, our engineering team works directly with heterogeneous accelerators and frontier silicon, including Cerebras, d-Matrix, Intel, NVIDIA, AMD, Normal Computing, Tenstorrent, GreatSky, and Mixx. We are not stopping at today's chips: each new generation of silicon unlocks algorithms that couldn't run before, and we intend to be first to them, every time. If we get it right, it will belong to everyone building on it - not to any single vendor.
In our latest funding round, we raised $100M, led by Atomico with participation from Plural, DCVC and the UK Sovereign AI Fund’s first investment. With this, we are building the infrastructure for the next era of intelligence.
We are engineers and scientists based in London, working across the full depth of the stack. We are curious, intellectually honest, and building what doesn't exist yet. If you thrive on uncharted territory and are energised by the scale of the challenge, we'd love to hear from you.
About the Role
Callosum believes that orders of magnitude improvements in AI systems will come through application-aware orchestration across heterogeneous hardware. We are building that vision: infrastructure that treats the full landscape of compute as a unified, co-evolving system, evolved beyond GPUs.
Inference engines were designed for single-model inference on homogeneous GPU clusters - this role builds them beyond that. Working directly on systems like vLLM and SGLang, you will adapt and extend them for heterogeneous resources, making them hardware-aware, with deeper optimisation around scheduling, memory, and execution. The execution strategies you design - parallelism, disaggregation, caching - will define what heterogeneous inference looks like at production scale. Your work ensures that the capabilities exposed by the lower layers of the stack translate into real, measurable gains, the new standard for how inference runs on diverse hardware.
What You'll Build
Contribute upstream to SGLang and vLLM, and maintain internal forks where our requirements diverge
Improve hardware-awareness within inference engines so that scheduling, memory management, and execution adapt to the capabilities of the underlying accelerator
Design and implement bespoke parallelism and disaggregation strategies that go beyond default configurations to better exploit heterogeneous hardware
Work closely with an Accelerator Systems Software engineer to ensure engine-level abstractions map cleanly onto diverse hardware capabilities
What Sets You Apart
Deep familiarity with the internals of SGLang, vLLM, or comparable inference serving frameworks - scheduler design, memory management, and execution pipelines
Strong background in high-performance Python and C++/CUDA systems, particularly in the context of ML inference
Experience designing or implementing parallelism strategies for large model serving
Understanding of disaggregated serving architectures and the tradeoffs involved in separating modules of a workflow
Demonstrable record of working effectively in fast-moving open source codebases with evolving APIs and design conventions
What We Offer
Competitive Salary, determined by skills and experience
Equity & Ownership
Private 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.
This description is the source posting as it read when we added it. We are not affiliated with CALLOSUM LTD, so check their own site for the current details.
Where this offer sits in the market
Programmers and software development professionals (SOC 2134) · UK · ONS ASHE 2025 · basic pay · ~399k in sample- Middle half £42,536–76,752
- Median £56,784
- Going rate £54,700
- Threshold £41,700
- New entrant £38,300–49,200
Similar sponsored roles
See all UK visa jobsNo close matches live right now.
Browse more sponsored jobs at CALLOSUM LTDAbout sponsorship for this role
Does this job guarantee visa sponsorship?
Not necessarily. CALLOSUM LTD holds a sponsor licence, but sponsorship for a specific hire is always the employer's decision. Be upfront in your application that you'll require it.
What salary is needed for this role to be eligible?
The offer must clear both the general threshold and the SOC 2134 going rate of £54,700. New-entrant and shortage discounts can lower it.