01
Period tracking
The dates. On the device.
OnyxRhythm
Get the app →
OnyxRhythm
Get the app →
Play Store liveOfflineNo pink
Your cycle. Your control.
Not a pink social network.
Periods, symptoms, a fertility window — on the device. No community. No advice. Just the data. The big apps store cycles on servers that can be asked for them. This one cannot, because it never received them.
Google Play is live. App Store listing is not public yet. Detect my phone →
Launch news: Google Play launch, April 21, 2026 →
See how it works01 — The problem
Period apps with accounts keep reproductive data where a court can reach it. Some have already been fined for sharing it.
OnyxRhythm is the other architecture: dark, quiet, on the device. No community. No advice column. No pink. Play Store is live.
02 — The job
A calendar. Not a forum.
01
The dates. On the device.
02
What you felt. Not a crowd average.
03
From your data. Not a social prediction.
04
No panic copy.
05
Built for people who did not want the pastel clinic.
06
Nobody else is in this calendar.
03 — The app
A real screen. Later interiors are still placeholders in the current build — we are not replacing them with fake UI.
04 — Proof
05 — Privacy
We cannot hand over data we never received.
OnyxRhythm is a personal calendar. It is not a medical device, not contraception advice, and not a fertility clinic.
06 — Price
Subscription only. No free tier. No trial. Cancel in your store account.
Cycle pass
Included: periods · symptoms · window · reminders · offline · no ads
07 — FAQ
No.
No.
Yes.
Yes.
No.
$0.99 per month or $9.99 per year. Subscription only. No free trial.
No.
OnyxRhythm is the cycle tracker that cannot be asked for data it never held.
Google Play is live. App Store listing is not public yet. Detect my phone →
Sending this to a friend? One QR. The phone opens the right store when it exists — or this page until then.