Harmonic (Aristotle)
Math-reasoning AI from Robinhood CEO Vlad Tenev, using formal proofs to give hallucination-free answers.
Overview
Harmonic builds Aristotle, an AI reasoning engine focused on 'mathematical superintelligence.' It translates natural-language math problems into the Lean 4 proof assistant, so answers are formally verified rather than merely plausible. In 2025 Aristotle reached gold-medal-level performance on the International Mathematical Olympiad, delivering verified solutions to five of six problems. Co-founded in 2023 by Robinhood CEO Vlad Tenev and Tudor Achim, Harmonic raised a $120M Series C in November 2025 at a $1.45B valuation. A consumer app is available on iOS and Android.
Pricing
Pricing shown for reference only. These figures reflect RECATOOLS research as of 24 Jul 2026 and may be out of date or incomplete. This is not financial or purchasing advice — always confirm the current price on the provider’s official website before making any decision.
ASEAN Perspective
Harmonic (Aristotle) in Southeast Asia
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What this is for: Solving and formally verifying mathematical problems using the Lean proof assistant to avoid hallucinated reasoning.
Who this is for: Mathematicians, researchers, students and developers who need trustworthy quantitative reasoning.
Availability: Free consumer app on iOS and Android, with paid API access for larger workloads.
What people say
Harmonic's Aristotle got its credibility from a headline result: at the 2025 IMO it produced formally verified Lean 4 proofs for five of six problems, gold-medal-level performance, and technical observers (including Sequoia's IMO write-up) singled it out as the most rigorous of the three AI teams because its answers were machine-checked rather than needing human grading. That formal-verification approach is the core of its "hallucination-free" pitch, and investors bought in — a $120M Series C in November 2025 valued the company at $1.45B.
The scepticism centres on that same "hallucination-free" marketing. Critics note the claim is narrow: it holds only for statements Aristotle can express and prove in Lean, not for open-ended math chat, and the IMO run was done under formal (autoformalised) conditions, not natural language. Reviewers also observed the Lean requirement forces the system to justify every step, which slowed it and, on at least one problem, caused it to run out of time before completing a proof.
As a consumer app the beta is new and lightly reviewed, so there is little G2/app-store signal yet. The fair summary: a genuinely rigorous, verification-first approach that impressed mathematicians, wrapped in bolder marketing than the current product reliably delivers.
Summary of public user & expert reviews, compiled by RECATOOLS.
About this listing
This entry was compiled from publicly available data including Harmonic (Aristotle)'s official website, press releases, documentation, and reputable third-party publications. RECATOOLS is not affiliated with Harmonic (Aristotle) unless explicitly stated.
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