Callosum raises $100m seed round to build the Intelligent Systems layer for the heterogeneous era of AI
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Callosum, the AI infrastructure company founded by Cambridge scientists Danyal Akarca and Jascha Achterberg, today announced a $100 million seed financing, one of the largest seed rounds ever raised in Europe, to rewrite how AI is computed.
Callosum has built the software layer that co-optimises AI models and chips, orchestrating each workload across the hardware best suited to run it, removing the engineering complexity of achieving frontier performance.
The round was led by Atomico, with participation from Plural, DCVC, UK Sovereign AI, and other world leading investors. It comes less than six months after Callosum emerged from stealth with a $10.25 million pre-seed round, reflecting growing conviction that the economics of AI computing will be restructured by Callosum.
The next era of AI will not be won by scale alone. Frontier models offer extraordinary capability, but their cost has grown unsustainably. At the physical level, the one-chip-fits-all approach has imposed unacceptable structural risks on every buyer, developer and nation state. Callosum is breaking both of these homogeneities by building a dynamic, intelligent system to deliver each workload what it actually needs:speed, cost, and precision.
Callosum was Sovereign AI’s first-ever investment, which the Fund described as “deep technical infrastructure that shapes how AI is computed globally, built and anchored in the UK.” Britain firmly believes that national AI capability is not built on any single frontier model or chip, but on the dynamic infrastructure that can unlock the full potential of both. Sovereign AI announced that it was investing in Callosum, in April, with today’s funding round making that commitment official.
AI Minister Kanishka Narayan said: “AI is nothing without the chips that underpin it – and the eye-watering demand for them is only going to grow. In the race to develop and use AI, success will depend not just on having access to those chips, but on using them as efficiently as possible“. That’s exactly what Callosum are working on. By helping AI systems match the right computing power to the job they’re carrying out, they are laying the foundations for AI that is more capable, affordable and able to benefit far more people. “We saw Callosum’s potential back in April when we announced Sovereign AI’s plans to invest, and it’s brilliant to see other leading funds backing them today, too.”
New unit economics for AI
Callosum’s opportunity stems from a structural shift in the AI industry. Spending is rapidly moving from training ever-larger foundation models towards better inference, while at the same time, a Cambrian explosion of specialised processors – from wafer-scale to analog and optical computing – is challenging the era of single, monolithic chips.
Callosum sees this emerging diversity—across models and chips—as a massive opportunity. At the heart of Callosum’s thesis is a reframing of the industry’s basic unit of value: the token. Rather than just making tokens cheaper by brute force, Callosum’s heterogeneous approach makes each token worth more – every unit of computation directed to the model and hardware where it produces the most useful intelligence per amount of money spent.
“The industry has been betting that one model or one kind of chip will rule them all,” said Danyal Akarca, Callosum’s Co-founder and CEO. “But nature shows us the opposite. Intelligence is collective and will emerge from many specialised systems working together. We believe AI needs a new axis of scaling, where many models and hardware co-evolve as a single system. That’s how we build AI that is not only more capable, but dramatically faster, more affordable and far more energy-efficient, opening the door to applications that were not viable before.”
A software layer for Heterogeneous Intelligence
Alongside the raise, Callosum is launching the first software layer built for heterogeneous intelligence: an orchestration platform that decomposes AI workloads and distributes each task to the model and processor best suited to execute it. The result is inference tailored to the task needs, unlocking gains in cost, speed and capability that no single model or chip can reach alone.
As the orchestrator of intelligent systems, Callosum serves three groups shaping the next phase of AI:
- Enterprises consuming tailored inference who need frontier AI capability at cost and latency points now unobtainable.
- Next-generation clouds and hyperscalers serving tailored inference, needing to orchestrate diverse fleets of models and chips.
- Sovereign compute programmes benefitting from resilient, heterogeneous AI capacity.
The company is launching its tailored inference through a first product: a family of APIs to let developers adopt frontier AI hardware without rewriting their applications, collapsing what is often months of engineering work into a single integration.
“AI is entering a new era, where intelligence won’t be defined by a single model or a single chip, but by systems that can enable the best setup for the job. Callosum is building the infrastructure layer that will make that possible. The team has already demonstrated world-class technical breakthroughs, and incredible speed of execution, and we believe their vision has the potential to fundamentally reshape how AI is deployed at scale. We’re proud to partner with them as they build the foundation for the agentic era.” said Sasha Vidiborskiy, Partner, Atomico.
Callosum’s tailored-inference platform is already in production. On complex agentic workloads in financial services, the platform ran 4x faster, cut compute costs by 70% and improved task success rates by 10% versus the same workloads on a single frontier model running on conventional GPU infrastructure. These results are part of Callosum’s partnership with Cerebras, the US chipmaker whose wafer-scale processors are among the fastest available for AI inference. Cerebras has partnered with Callosum on a shared bet for the new infrastructure paradigm.
Global heterogeneous partnerships reshaping AI sovereignty
Callosum is building a global network of silicon partnerships that includes Rebellions (South Korea), Axelera (Netherlands), Tendrils (UK), as well as key infrastructure partners including Supermicro. What Callosum is building is larger than the sum of its parts: each technology brought into the systems is co-optimised.
“Orchestration is all you need,” said Jason Pontin, General Partner, DCVC. “Token consumption by users of scientific and enterprise computing is expanding exponentially, but Callosum knows the key to making each token cheaper and more valuable is to treat AI computing as multimodal, not monolithic. Their talent for orchestrating workloads across heterogeneous computing resources is rooted in their deep understanding of which jobs are best for which models and chips.”
Callosum answers the call of governments and enterprises worldwide seeking greater technological resilience. Its model shifts the balance of power away from any single model or chip provider: if workloads can move fluidly across both models and hardware, no vendor holds a chokepoint over a nation’s or a company’s access to intelligence.
“AI sovereignty isn’t about owning a chip fab. It’s about never being hostage to one.” said Jascha Achterberg, Co-founder of Callosum. “It’s about building systems that can harness the best intelligence wherever it exists. By running AI across many different chips and architectures, we create systems that are more resilient, more efficient and less dependent on any one company or country. That’s how you build AI infrastructure that can endure.”
Callosum is a founding member of the Scaling Inference Lab at ARIA, the UK’s advanced research agency, where it is integrating emerging technologies from companies including Oriole Networks and Lumai – which use light rather than electricity to move and process data – into large-scale AI systems.
The funding will be used to scale the technology, deepen partnerships across silicon ecosystems, and expand the team. A selection of Callosum’s tailored-inference APIs go live today; further customer deployments and partnerships will be announced in the coming months.
The founders, Danyal Akarca and Jascha Achterberg, met while earning their PhDs at Cambridge, where their research examined how the brain achieves intelligence not by replicating one type of neuron billions of times but by combining specialised circuits. They argue AI systems will follow the same pattern: many models, interacting collectively, on diverse computing substrates.
“The brain has inspired many of our great breakthroughs in AI. Within the brain, the corpus callosum joins our two specialised hemispheres with intelligence emerging not from any one part, but from their connection.
Sebastian Hunte, Investment Director, AlbionVC
In compute, as in the brain, heterogeneity creates rich emergent structure: systems more capable than the sum of their parts. Running frontier AI on homogeneous infrastructure is still an order of magnitude too expensive and too slow. But the disaggregation of the serving stack, multi-agent workflows, and optionality across models and hardware opens up a system-level co-optimisation surface that can deliver exactly those gains.
Callosum does this better than anyone else in the world.
Danyal Akarca and Jascha Achterberg have the ambition, intellectual intensity and conviction to build a generational company. One capable of shaping the frontier of a sector that will define the next 30+ years of global social and economic order. Backing companies with this scale of mission, a technical edge that compounds towards vertical value capture, and truly gifted, obsessive founders is the reason we do what we do. There was never a doubt we would back them.”
