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Luteal vs Euki: catalog facts
Luteal	Euki
Free Free and open source under GPL-3.0-or-later.	Free Free to use with no paywalls, supported by donations.
Android	Android, iOS
Labels recorded observations separately from estimates Tracks symptoms and basal body temperature	Period and pregnancy tracking Available in English and Spanish
Android only. Predictions are estimates; the app makes no diagnosis.	Available for Android and iOS
Downloadable app	Downloadable app
Open source	Open source
License: GPL-3.0-or-later	License not stated
Not stated if an account is needed	Not stated if an account is needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked October 8, 2026	Official website Full listing and sources Checked October 8, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.