Callosum raises $100 million seed to route AI workloads across mixed chips

London-based Callosum raised a $100 million seed round to build software that routes AI workloads across a mix of models and specialized chips rather than one vendor’s hardware, the company said on August 20, 2026. Atomico led the round, with Plural, DCVC and the UK Sovereign AI Fund taking part.

Callosum, founded in 2025 by Danyal Akarca and Jascha Achterberg, calls its product Tailored Inference. Instead of pinning an AI workload to one chipmaker, the software matches each task to whichever model and processor can run it most cheaply or quickly across a fleet of mixed hardware. The pitch lands as companies hunt for ways to cut inference costs and loosen their dependence on any single supplier.

Alongside the raise, Callosum announced a partnership with Cerebras, the maker of wafer-scale AI chips, plus deals with the chip startup Rebellions and other infrastructure providers and hardware makers. Those relationships give its routing layer more back-ends to send work to.

The round ranks among the largest AI seed rounds in Europe. Callosum had previously raised about $10.25 million, bringing its total funding to roughly $110 million since it was founded last year.

The claim to prove is technical. Routing across heterogeneous chips means handling different software stacks, memory models and performance profiles without erasing the savings in overhead. Early partnerships signal intent; sustained cost cuts on production workloads will be the test.