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The best private period trackers in 2026

Ranked by one question: how little about your cycle leaves your phone, and how sure you can be of that. Splash is ours, and we say so wherever it appears.

In short: The most private period trackers keep data on your device and need no account. Euki, a free open-source app, was Mozilla’s top-scored tracker in July 2026; drip is open source too; Apple Health is end-to-end encrypted in iCloud; Splash is local-first with optional end-to-end encrypted sync and free partner sharing. We make Splash, so every claim is sourced and dated 28 October 2026.

Last reviewed . Written by Splash. No affiliate links.

The short version

  • Private with sync and partner sharing: Splash (no account, optional end-to-end encryption, every feature free).
  • Local-only, no sync: Euki (non-profit, 10 out of 10 in Mozilla’s July 2026 review).
  • On iPhone: Apple’s built-in Cycle Tracking (end-to-end encrypted in iCloud with two-factor authentication).
  • Need contraception? Natural Cycles is FDA-cleared; privacy-ranked trackers here are not.
Splash settings screen showing where your data is kept

How we ranked them

Does it work without an account?
No account means nothing ties your cycle to your name or email.
Where do logs live by default?
On your phone is best. On a server, it matters who holds the key.
Is sync end-to-end encrypted?
If the company can’t read it, it can’t share or lose it in readable form.
Can you check what they hold?
A specific, public list of what the server can see beats a promise.
Is it clear what is collected?
Plain, specific privacy pages, not slogans.

How they compare at a glance

Private period trackers compared Last checked
FeatureEukiSplashApple HealthdripClueFlo
No account neededYesYesApple IDYes–Anonymous Mode
Data stays on device by defaultYesYesOn device + iCloudYesNoNo
Partner sharing–Free––PlusBasic free
Mozilla July 2026 review10 / 10Not reviewedNot reviewedNot reviewed8 / 107 / 10

Mozilla’s July 2026 review tested six trackers: Euki, Clue, Flo, Period Calendar, Spot On and Stardust. It scored Stardust 2 out of 10, after TechCrunch reported it was the only one sending sensitive health data to another company. Splash, Apple Health and drip were not in that review. A dash means we could not confirm it from a public source.

The list

  1. Euki

    Best for: Maximum privacy, open source

    Free, non-profit, open source, local-only, with a PIN, decoy screen and auto-delete. Mozilla’s top scorer in July 2026 (10 out of 10).

    Worth knowing: No sync between devices, so data is lost with the phone; no partner sharing.

    Full comparison with SplashEuki websiteSource: Euki (official site)Source: Mozilla Privacy Not Included: EukiSource: DH Insights: Mozilla report reveals wide privacy gaps among popular period tracking apps (30 Jul 2026)

  2. Splashour app

    Best for: Free, no account, encrypted partner sharing

    Local-first with optional end-to-end encrypted sync; doctor report, symptom guide, library and every mode free.

    Worth knowing: Installs from your browser in seconds, and imports your Flo or Clue history. Not yet independently reviewed by Mozilla.

  3. Apple Health Cycle Tracking

    Best for: iPhone and Apple Watch users

    Built in and free; end-to-end encrypted in iCloud with two-factor authentication; wrist-temperature ovulation estimates and a 12-month PDF for your doctor.

    Worth knowing: Apple devices only.

    Full comparison with SplashApple Health Cycle Tracking websiteSource: Apple Support: Track your menstrual cycle (Cycle Tracking), published 14 Sep 2026

  4. drip

    Best for: Sympto-thermal charting, open source

    Open source, and everything you enter stays on your device; built around temperature, mucus and cervix charting.

    Worth knowing: Plain design; no sharing or sync.

    drip websiteSource: drip (official site)

  5. Clue

    Best for: Science-led content, EU jurisdiction

    Named clinician authors, Berlin-based under GDPR, free version available. Scored 8 out of 10 in Mozilla’s July 2026 review.

    Worth knowing: Sharing, Conceive and Perimenopause modes need Clue Plus; account needed to share.

    Full comparison with SplashClue websiteSource: Clue on the App StoreSource: Clue support: How can I share my cycle using Clue Connect?Source: Clue support: What’s Clue Perimenopause mode?Source: DH Insights: Mozilla report reveals wide privacy gaps among popular period tracking apps (30 Jul 2026)

  6. Flo

    Best for: Big library and community

    Very large library (Flo says 100+ health experts), free Anonymous Mode using Oblivious HTTP, basic partner sharing free. Scored 7 out of 10 in Mozilla’s July 2026 review.

    Worth knowing: Doctor report (iOS), Symptom Checker (not in the UK) and expert courses need Premium.

    Full comparison with SplashFlo websiteSource: Flo: Anonymous Mode FAQSource: Flo help centre: Do I need a subscription to access Flo for Partners? (posted 3 Oct 2024)Source: Flo help centre: What is included in Flo Premium (posted 4 Oct 2024)Source: DH Insights: Mozilla report reveals wide privacy gaps among popular period tracking apps (30 Jul 2026)

  7. Natural Cycles

    Best for: App-based contraception

    FDA-cleared as birth control; uses temperature, including from wearables.

    Worth knowing: Paid subscription; needs consistent temperature measurement.

    Full comparison with SplashNatural Cycles websiteSource: FDA: FDA allows marketing of first direct-to-consumer app for contraceptive use (Aug 2018)Source: FemTech Insider: Natural Cycles launches perimenopause mode and NC° Band (Oct 2025)

Want to try the one that keeps your cycle on your phone and still lets you share it? No sign-up.

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Want the detail? See the full comparison table or exactly what Splash’s server can see.

Questions about private period trackers

What is the most private period tracker?

Euki is the most private tracker we can source: it is open source, run by a non-profit, stores data only on your device, and scored 10 out of 10 in Mozilla’s July 2026 review. drip is similar. Splash is local-first with no account, and adds optional end-to-end encrypted sync and sharing.

Do period tracker apps sell your data?

Practice varies. In 2022 a review of 25 period apps by ORCHA found 84% sent data beyond the developer’s own systems, and Mozilla labelled 18 of 25 period and pregnancy products with a warning. Mozilla’s July 2026 review of six trackers found only one, Stardust, sending sensitive health data to another company.

Is a period tracker with no account private?

Usually more private, because nothing ties your cycle to your name or email, and data tends to stay on the device. It is not a guarantee: check whether the app has analytics or advertising code, and what backup or sync does. Splash has no analytics or ad code, and without an account nothing about your cycle reaches us.

What should I check before choosing a private period tracker?

Check five things: whether it works without an account, where logs are stored by default, whether sync is end-to-end encrypted, whether the company publishes what its server can see, and whether independent reviewers such as Mozilla have tested it. A specific, public list beats a slogan.

What changed at the last review

  • : Added Mozilla’s July 2026 review (Euki 10, Clue 8, Flo 7, Stardust 2 out of 10, as reported by DH Insights and TechCrunch); moved the ranking rationale into a sourced table; added questions and answers.

Sources

  1. Euki (official site) accessed 2026-10-26
  2. Mozilla Privacy Not Included: Euki accessed 2026-10-26
  3. DH Insights: Mozilla report reveals wide privacy gaps among popular period tracking apps (30 Jul 2026) accessed 2026-10-28
  4. Apple Support: Track your menstrual cycle (Cycle Tracking), published 14 Sep 2026 accessed 2026-10-28
  5. drip (official site) accessed 2026-10-26
  6. Clue on the App Store accessed 2026-10-26
  7. Clue support: How can I share my cycle using Clue Connect? accessed 2026-10-26
  8. Clue support: What’s Clue Perimenopause mode? accessed 2026-10-28 (Clue blocks automated fetching; read through a search excerpt.)
  9. Flo: Anonymous Mode FAQ accessed 2026-10-26
  10. Flo help centre: Do I need a subscription to access Flo for Partners? (posted 3 Oct 2024) accessed 2026-10-28
  11. Flo help centre: What is included in Flo Premium (posted 4 Oct 2024) accessed 2026-10-28
  12. FDA: FDA allows marketing of first direct-to-consumer app for contraceptive use (Aug 2018) accessed 2026-10-26
  13. FemTech Insider: Natural Cycles launches perimenopause mode and NC° Band (Oct 2025) accessed 2026-10-26
  14. Mozilla Foundation: Nothing Personal, period and ovulation trackers (16 Jul 2026) accessed 2026-10-28 (Mozilla’s page blocks automated fetching. The findings used here are checked against the two reports listed next to it.)
  15. TechCrunch: Period tracker Stardust shares users’ health data with analytics firm, says Mozilla research (16 Jul 2026) accessed 2026-10-28
  16. Mozilla Foundation: In post-Roe era, Mozilla labels 18 of 25 popular period and pregnancy tracking tech with a Privacy Not Included warning (Aug 2022) accessed 2026-10-28 (Mozilla’s page blocks automated fetching; read through search excerpts.)
  17. Digital Health: ORCHA research identifies privacy issues with period tracking apps (29 Jul 2022) accessed 2026-10-28 (Read through a search excerpt.)
  18. Flo: Premium membership (free vs Premium table) accessed 2026-10-26
  19. Clue support: How much does Clue Plus cost? accessed 2026-10-26
  20. FDA 510(k) K193330: BioWink GmbH (Clue Birth Control), Feb 2021 accessed 2026-10-26
  21. Natural Cycles help: How does the subscription work? accessed 2026-10-26
  22. Stardust (official site) accessed 2026-10-26

More: Is my period tracker data private? · Period tracker without an account

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Splash screen showing where your data is kept.