Theorem is a San Francisco-based startup from Y Combinator’s Spring 2025 batch that automates the formal verification of software produced by AI coding assistants. Its platform blends classical formal methods with proprietary AI models trained to automatically generate and check mathematical proofs, shrinking work that once took PhD-level engineers years down to days or weeks. Central to the product is a “fractional proof decomposition” approach that allocates verification effort according to the criticality of each code component, enabling scalable oversight of large, complex systems. The team believes the next bottleneck in software development will be trust, not code generation, as tools from GitHub, Amazon and Google already create billions of lines of code annually. Early collaborations are under way with customers in AI research labs, electronic design automation, and GPU-accelerated computing, and the company recently uncovered a bug that evaded Anthropic’s internal tests. The $6 million seed financing provides capital to expand the product’s reach and address a widening “supervision gap” threatening critical infrastructure. No revenue or user numbers have been disclosed.

Total raised

$6M

Funding rounds

1

Latest round

Seed

Latest activity

Jan 2026