Clair
A cycle-aware health companion that explains what your hormones are doing, in plain language.
Clair reads your cycle from Apple Health, estimates which hormones are leading each day, times medication reminders to your cycle and explains it all in plain language. A working prototype exists; the redesign for the App Store version is done and the rebuild is planned. Estimates, not medical advice.
The problem
Most period trackers stop at dates. They say when the next period is due, but not what is happening in between: which hormone is leading, how that tends to feel, when a migraine window opens, or when a medication should be taken.
A period tracker tells you when. Clair tells you what’s coming.
Who it is for
People who track their cycle and want to understand it, especially anyone whose migraines, mood or medication follow it.
The redesign plans for different life stages from the start: a natural cycle, the pill, a hormonal IUD or implant, pregnancy and postpartum, perimenopause, and irregular cycles or PCOS. Each changes which estimates appear.
Savannah Black's role
Savannah Black founded Clair through Susumu House and owns all of it: product, brand, design and engineering.
A working prototype came first, in March 2026, built in SwiftUI under the name Perenne and then renamed Clair. In October 2026 Savannah reviewed it against what the App Store and a health app need, and designed its replacement: Night, with a design system, the Quarters icon, every screen and its options, a website, a light theme and a ten-week rebuild plan.
Key decisions and trade-offs
Taken from the redesign canvas and its review and rebuild plan.
Everything stays on the phone
Predictions run on the device, with no account and no server. Health data is never stored in iCloud, and a password-protected backup covers what Health does not.
Night: one phase colour at a time
Dark surfaces told apart by tone rather than borders, Geist as the only typeface, and four phase colours used one per screen so the current phase is always the loudest thing on it.
Two-way Apple Health
Health becomes the shared record. Clair reads new and changed samples incrementally and writes what you log back with sync identifiers, so editing a day never creates a duplicate.
Your body is free
Logging, predictions, Health sync and data export are always free. Clair Plus charges for planning around your cycle: cycle-timed reminders, migraine alerts, calendar sync and insights.
Estimates, said plainly
"Estimates, not medical advice" in the app, "Not for contraception" beside every fertile window, and the hormone chart labelled as a typical curve, not measured levels. The plan includes a clinical review of the Learn copy and the migraine logic.
Fix what would fail first
The review ranked the prototype’s issues by risk. Top of the list: a store that deleted itself on any schema change, an unused clinical-records entitlement, a Google sign-in that could not work, and phase and ovulation estimates that disagreed on long cycles.
What exists today
- A SwiftUI prototype with SwiftData that reads menstrual flow, basal temperature, ovulation tests and cervical mucus from Apple Health
- On-device estimates of hormone phase and migraine risk, with confidence that grows with each logged cycle
- Medication reminders kept inside iOS’s 64-notification limit with a rolling 30-day window
- The Night redesign: 41 boards covering the design system, the icon, three Today layouts, cycle, meds, logging, onboarding, Learn, settings, sync, Clair Plus, edge cases, privacy, a website and a light theme
- A review of the prototype and a rebuild plan with seven phases, an App Store checklist and the decisions still open
What's next
The rebuild plan, about ten weeks of work:
- Foundations, then the cycle, hormone and migraine engines moved into their own package with tests for 21 to 40 day and irregular cycles
- The Night design system and every screen, replacing the prototype one tab at a time
- Two-way Health sync and a Clair calendar through EventKit
- Clair Plus with StoreKit 2, then widgets, VoiceOver and the rest of the polish
- TestFlight with people who track their cycle, then App Store submission
- Still open: which Today layout, the tab bar, prices, the first market and a trademark check on the name
Screens
From the redesign, in its light theme. These are designs for the App Store version, not yet built; dates, doses and phases are sample content.
Identity
Quarters: four rounded arcs in four shades of the brand purple, readable down to 29 px. Inside the app the same ring carries the four phase colours, and the wordmark is set in Geist Light. Night is the default theme; the light theme uses the same tokens.
