Privacy Policy
Last updated: 16 August 2026
This policy explains how Wattmark ("the app") handles your information.
1. Who we are
- Provider: Yodaka LLC (合同会社ヨダカ)
- Contact: support@wattmark.app
2. No account, no identity
The app requires no sign-up. We do not collect your name, email address, phone number or postal address.
3. What never leaves your device
The following is stored on your device only and is sent to no one, including us:
- Imported ride data (the contents of your FIT files, including power, heart rate, cadence, altitude and location)
- Computed metrics (weighted power, load, power curve, FTP estimates and so on)
- Your profile (weight, total weight, age, sex, goal, weekly riding time)
This data lives in files on your device and is excluded from iCloud backup.
4. What we send for AI analysis
Only when you request an AI analysis, the following is sent through our server (Cloudflare Workers) to Anthropic PBC's Claude API:
Sent
- A ride summary (duration, distance, elevation gain, power / heart rate / cadence statistics, per-lap figures, and the metrics we computed)
- The parts of your profile the analysis needs (weight, goal, weekly riding time)
- Your display language
Never sent
- GPS coordinates. Not once. The app strips them, and our server rejects any request that contains them
- Your name, email address, or anything else that identifies you
- The FIT file itself
We ask for your consent before the first transmission. If you decline, everything except the AI analysis — all metrics and charts — still works. You can withdraw consent at any time in Settings.
See Anthropic's privacy policy for how they handle it.
5. Anonymous identifiers
To prevent abuse and runaway cost, we use:
| What | Why | Where and how long |
|---|---|---|
| Anonymous device ID (a randomly generated UUID) | Rate limiting and the free-analysis allowance | Our server's KV store; expires automatically within days |
| Subscription identifier | Checking subscription status | RevenueCat, Inc. |
The anonymous device ID is a random value generated on your device. It is unrelated to Apple's advertising identifier (IDFA) or any hardware identifier, and we cannot identify you from it.
6. Subscriptions
Subscriptions are managed through RevenueCat. Payment itself is handled by Apple; we never receive your card details.
7. Third parties
Apart from those named above (Anthropic, RevenueCat, Apple, and our infrastructure provider Cloudflare), we do not share or sell your information. The app carries no advertising and does no tracking for advertising purposes.
8. Deleting your data
"Delete account and data" in Settings removes every ride, metric, profile field and the anonymous device ID from your phone. Deleting the app does the same.
What remains on our side is an unexpired counter keyed to the anonymous device ID, which expires on its own. You can also request deletion at the contact address above.
9. Children
The app is not intended for anyone under 13.
10. Changes
If this policy changes, we will update the date at the top of this page. Material changes will also be announced in the app.