Compare software

Clue vs Periodical: catalog facts
Clue	Periodical
Best for: People who want to track their menstrual cycle on their phone	Best for: Android users who want a private, open-source period calendar
Free + paid options Free app with a paid subscription for additional features.	Free Free and open source under the GPL-3.0-or-later licence.
Android, iOS	Android
Cycle predictions and personalised insights Available on both iOS and Android All 3 strengths for Clue Cycle predictions and personalised insights Available on both iOS and Android Science-based approach to content	Calculates fertile days and tracks symptoms and notes Backup to a single compressed file on local storage All 4 strengths for Periodical Calculates fertile days and tracks symptoms and notes Backup to a single compressed file on local storage Available from F-Droid, Google Play or as an APK Translated through a community Crowdin project
Some features require a subscription Sensitive health data is handled by a commercial service	Calendar method is not reliable for contraception Simple feature set compared with commercial cycle trackers
Downloadable app	Downloadable app
Not open source	Open source
License not stated	License: GPL-3.0-or-later
Not stated if an account is needed	Not stated if an account is needed
Not stated if it works offline	Not stated if it works offline
Official website Full listing and sources Sources for Clue helloclue.com play.google.com/store/apps/details apps.apple.com/us/app/clue-period-cycle-tracker/id657189652 Catalog checked September 23, 2026	Official website Full listing and sources Sources for Periodical arnowelzel.de/projekte/periodical f-droid.org/packages/de.arnowelzel.android.periodical Catalog checked October 2, 2026

“Not stated” means we have not confirmed it. Features can vary by device and plan.