Harmonic was founded in 2023 by Vlad Tenev, co-founder and CEO of Robinhood, and Tudor Achim, who serves as CEO. The company's mission is to build 'mathematical superintelligence' (MSI): AI systems whose answers are not merely plausible but formally provable. Harmonic's central insight is that large language models hallucinate because their outputs are statistically generated rather than verified, and that mathematics offers a path to certainty through formal proof.
Harmonic's flagship model, Aristotle, integrates frontier AI with the Lean 4 proof assistant so that mathematical claims can be machine-checked rather than trusted on faith. This formal-verification backbone is intended to eliminate hallucinations in the domains where Harmonic operates. In 2025 Aristotle achieved formally verified gold-medal-level performance on the International Mathematical Olympiad, among the most prestigious competitions in mathematics, and the company reports leading positions on formal-math benchmarks such as ProofBench. Harmonic has also released Aristotle as a consumer-facing math app and exposes an API for developers.
The company has raised capital rapidly across three rounds: a $75 million Series A led by Sequoia Capital in September 2024, a $100 million Series B led by Kleiner Perkins in July 2025 at a nearly $900 million valuation, and a $120 million Series C in November 2025 led by Ribbit Capital at a $1.45 billion post-money valuation, bringing total funding to roughly $295 million. Investors across these rounds include Sequoia, Index Ventures, Kleiner Perkins, Paradigm, Ribbit Capital and Emerson Collective.
Harmonic sits at the frontier of a fast-emerging category of formal-reasoning AI companies, alongside players like Axiom Math and Axiomatic AI, all betting that Lean-based verification is the key to trustworthy machine reasoning. Beyond competition math, Harmonic envisions verified reasoning underpinning scientific discovery, engineering and software correctness, where guarantees, not guesses, are essential.