Questions

Which of these three is cheapest?

Nara Baby is free with no paid tier at all. Rhythm's tracking and predictions are free on one device, with sync at $5/mo per household. Huckleberry's caregiver sync is free, but its SweetSpot predictions require Plus at $11.99/mo.

Which one computes sleep predictions automatically?

Rhythm and Huckleberry both compute a prediction from a baby's logged sleep and age. Nara Baby instead has you choose wake windows yourself from a published age chart.

Do any of them require an account to start?

Rhythm does not; open the page and log the first event, and an account is only needed for sync. Huckleberry and Nara Baby both require an account from setup.

Can I import from Huckleberry into Rhythm?

Yes. Export your Huckleberry data and use Settings, Import, Huckleberry in Rhythm; the import guide lists exactly what comes across.

No account, no install, nothing to uninstall if it is not for you.

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