Harmonic

Harmonic is an AI research company building a state-of-the-art mathematical reasoning engine in pursuit of mathematical superintelligence. Co-founded in 2023 by Vlad Tenev (Co-Founder and CEO of Robinhood) and Tudor Achim (former Co-Founder and CTO of Helm.ai), the company is developing AI systems that use formal verification methods — specifically the Lean proof assistant — to produce verifiably correct and interpretable mathematical outputs, eliminating the hallucination problem endemic to large language models. Harmonic's flagship model, Aristotle, is designed to solve open problems in mathematics, accelerate verified software synthesis in safety-critical domains, and transform how mathematics is learned and taught. In 2025, the company raised $120 million at a $1.45 billion valuation, backed by Sequoia, Kleiner Perkins, Index Ventures, Paradigm, Ribbit Capital, and DST Global.