Beta

Join the beta.

Play Lemma on TestFlight on iPhone for two weeks before Lemma opens to everyone on 31 October 2026, and tell us what to fix.

What to test

• The daily lemma, from the first cell to the Proven screen.
• Hints: do they explain the move in words you understand?
• Circles: invite someone, prove the same lemma, compare times.
• Reminders: do they arrive when you asked for them?
• Lemma Plus, in the sandbox, at no charge: corollaries and the archive.

How to join

Write to us from the iPhone you want to play on. We reply with a TestFlight invitation; tap it, then tap Install.

You need an iPhone on iOS 18 or later. The beta is free and ends when Lemma opens to everyone. We keep very little about you; see the privacy policy.