Hadalog
Hadalog makes "why is my skin different today?" visible as an overlap of weather and daily habits. No camera, no photos of your face.
Download on the App StoreHow it works
Tap through three questions — tightness, oiliness, unsettledness — on a five-point scale. It takes about fifteen seconds. If you own a moisture meter, you can enter its readings instead. Weather (humidity, temperature, UV, wind) and Health (sleep, steps, water, cycle) are gathered automatically for the items you allow, and treated as that day's inputs. In the evening, one tap tells the app how it actually went, and the forecast moves closer to your own patterns. After fourteen days of records, it switches from general patterns to your own.
What you get
| Feature | Free | Full Access |
|---|---|---|
| Today's skin condition index | ✓ | ✓ |
| Today's care suggestions | ✓ | ✓ |
| Daily entries and records (unlimited) | ✓ | ✓ |
| Evening check-back | ✓ | ✓ |
| Calendar and 7-day trend | ✓ | ✓ |
| Tomorrow's forecast and suggestions | — | ✓ |
| Long-range trends, factor correlations, cycle phase | — | ✓ |
| PDF export | — | ✓ |
| Local backup | — | ✓ |
Full Access is a one-time purchase ($9.99). It is not a subscription.
Your data
Your records and Health data never leave your device, and no account is needed. Only when fetching the weather is your location sent to Apple.
Health data is read only — the app never writes to Health. Notifications never mention your skin condition, so nothing sensitive shows on your Lock Screen.
Before you use it
Hadalog is a self-tracking app. It is not a substitute for medical diagnosis or care. If something concerns you and persists, please consult a dermatologist.
The index is a self-tracking guide worked out from your entries, the weather, and your habits.
Requires iPhone (iOS 26 or later). Apple Watch optional. Available in 33 languages.
About the Android version
An Android version of Hadalog is in preparation. It supports Android 9.0 and later and will be published on Google Play. It also supports Wear OS watches, not just phones.
Both implementations are checked against the same verification data so that the Android build calculates and judges exactly as the iOS one does. Storage and backup behaviour is described in the privacy policy.
We are not linking to a store page until it is live. We will announce it here and on the support page.
Hadalog
Available on the App Store, for iPhone and iPad.
View on the App Store