Period & Cycle Tracking

Period-tracking apps got a privacy reckoning in 2022 after Dobbs v. Jackson in the US. Hosted apps that store cycle data on their servers (Flo, Clue, Glow, Eve, Stardust, Natural Cycles) became potential subpoena targets. By 2026, the privacy-first / on-device / FOSS subset has matured. If you're in a state with abortion restrictions or just don't want this data in a third-party cloud, Drip, Euki, and Periodical are the answer.

Sister sections: Pregnancy & Baby Tracking, Apple Watch, Oura & Whoop, Mental Health Journaling, Health Data Privacy, Self-Hosted Personal Apps, Quantified Self DIY.

Privacy-first / FOSS (2026 defaults)

• ★ ★ Drip (formerly Bloodyhealth) — FOSS Android + iOS; completely on-device, no account, no cloud; symptothermal method (NFP) support; CSV export. The single best 2026 pick if privacy is the priority.
  • https://bloodyhealth.gitlab.io/
  • https://gitlab.com/bloodyhealth/drip
• ★ Euki — completely free, no account, no analytics, no internet required; iOS + Android; tracks period, contraception, sex, abortion; designed by Women Help Women + reproductive-rights groups specifically post-Roe.
  • https://eukiapp.com/
• ★ Periodical — FOSS Android; F-Droid; minimal; on-device; CSV export.
  • https://github.com/arnowelzel/periodical

These three are the answer for "I just want to log my cycle without my data leaving the device."

Hosted (paid + free)

• ★ Clue — paid (~$10/mo) + free; Berlin-based, GDPR-strict; the most-cited "trustworthy" hosted app, but data still lives on Clue's servers. Cycle-science-credentialed advisory board.
• Flo — paid + free; largest user base; 2024 settlement with FTC over data sharing with Facebook / Google; "Anonymous Mode" added post-Roe.
• Glow — paid + free; pregnancy + period; sister app Eve for younger users; dataset acquired by Carrot Fertility.
• Stardust — paid + free; viral 2022 launch; pivoted on privacy claims; verify current privacy policy.
• Ovia — paid + free; pregnancy-focused but has cycle mode.

FAM / NFP / fertility awareness

• ★ Natural Cycles — paid (~$90/yr); only FDA-cleared digital contraceptive in the US (basal body temp method); requires daily oral / wrist temp. Apple Watch + Oura Ring temperature integration since 2024-25.
• Read Your Body — paid (~$30/yr) + free trial; symptothermal charting; community.
• Kindara — paid + free; FAM tracker.
• Daysy — paid hardware (~$330) + paid sub; thermometer + algorithm; FDA cleared (~99% method-typical).

Wearable-integrated

• ★ Apple Health Cycle Tracking — free with iPhone / Watch (Series 8+ for wrist temp, Ultra for nighttime baseline); on-device + iCloud E2E; strong default if you're in the Apple ecosystem and want data control.
• ★ Oura Cycle Insights — paid sub; basal-temp-derived cycle tracking; the most-talked-about wearable cycle feature in 2024-25.
• Whoop "Period Coach" — paid sub.
• Garmin Cycle Tracking — free with Garmin watch; basic.
• Fitbit / Pixel Watch — free + Fitbit Premium tier.

Privacy considerations (read this)

• ★ Hosted apps can be subpoenaed. Period-tracking data has been used in pregnancy / abortion-related investigations in the US since 2022. Privacy policies change.
• Apple HealthKit / Google Health Connect are on-device by default. Don't let third-party period apps write to them if you're concerned, since other apps you grant access to can then read the cycle data.
• Anonymous Mode in Flo is opt-in but still hosted on Flo servers.
• Drip / Euki / Periodical never have your data leave the phone.
• See Health Data Privacy for jurisdiction-specific guidance.

Practical guidance

• ★ If in the US and concerned about post-Roe risk, Drip, Euki, or Periodical are the safest pick in 2026.
• Don't grant period-tracking apps Health / Health Connect read access unless you trust them; they can mirror data to their servers.
• Use a passcode / biometric lock on the app itself.
• Periodic CSV export for long-term backup; all three FOSS picks support it.
• Family / partner sharing — most hosted apps have it; FOSS picks don't, by design.

Cost / license honesty

• Drip / Euki / Periodical — completely free; FOSS; no account.
• Clue / Flo — free tier + ~$10/mo paid.
• Natural Cycles — ~$90/yr.
• Daysy — ~$330 hardware + sub.
• Apple Health Cycle / Oura / Whoop / Garmin — costs of the hardware / sub apply, no extra fee for cycle features.

Pick this if…

• US, post-Roe, privacy-first: Drip or Euki.
• Android, FOSS, simple: Periodical.
• Already in Apple Watch ecosystem, want polish: Apple Health Cycle Tracking.
• FDA-cleared digital contraception: Natural Cycles.
• Want a community / hosted polish + GDPR jurisdiction: Clue.
• TTC / fertility-focused: Read Your Body or Kindara, or wearable-integrated (Oura).
• Pregnancy-track now: see Pregnancy & Baby.