Privacy

What Kantetsu stores, and what it doesn't.

Last updated 14 July 2026

The short version

Kantetsu keeps your rules, your daily marks, and your notes on your own device. There is no advertising, no analytics, no tracking, and nothing is sold or shared with anyone. An account is optional and exists only so your history can move between your own devices.

Data stored on your device

When you use Kantetsu without an account, everything stays on your device and is included in your own device backups. That covers:

• The rules you write, and their schedules
• Your daily kept-or-broken marks
• Your daily reflection notes
• App settings

None of this leaves your device unless you create an account and choose to upload it.

If you create an account

An account is entirely optional and the app is fully usable without one. Sync is not yet available in the app; when it ships, it will work as described here.

Creating an account stores your email address and a hashed password. Sync is manual and directional — you choose to upload your history or download it, and nothing is transferred without you asking for it. Uploaded data is the same data listed above, held on servers operated for the Systems Atlas Project and used for one purpose: giving it back to you on your other devices.

Your email address is used to identify your account and to send password resets. It is not used for marketing, and there is no mailing list.

What Kantetsu does not do

• No advertising, and no advertising identifiers
• No third-party analytics or tracking SDKs
• No selling, renting, or sharing of your data
• No profiling, and no use of your data to train anything
• No access to contacts, photos, location, or health data

This website

This site sets no cookies and runs no analytics. It is served by Cloudflare, which processes standard request information such as IP address in order to deliver the page and protect against abuse.

Deleting your data

Deleting the app removes everything stored on your device. If you have an account, you can delete it from within the app, which permanently removes your account and all data uploaded with it from the server. Deletion is immediate and cannot be undone.

Children

Kantetsu is not directed at children under 13, and no data is knowingly collected from them.

Changes

If this policy changes, the revised version will be posted here with a new date above. Material changes will also be noted in the app's release notes.

Contact

Questions about privacy, or a request about your data: [email protected].