Privacy policy
The short version: everything you record in Nesteia stays on your iPhone, unless you choose to sync your history to your own private iCloud database. We run no servers, no accounts and no analytics. We cannot see your fasting history, and we do not want to.
1. Who is responsible
Serhat Dereli, trading as Nesteia, Bromley, United Kingdom, publishes the app and this policy and is the data controller for it. Questions to serhatdereli@icloud.com.
2. What the app stores, and where
The app keeps two kinds of record on your device. The first is your history:
- Your fasts: plan (built-in or custom length), start and end time, how each one ended, the reason you gave and how you felt at the end, the time zone it started in and the clock readings that show whether the phone's clock was changed while it ran, and, for each fast over 72 hours, your confirmation that a clinician is supervising it, that electrolytes are being monitored and that a graded refeed is planned.
- Weight entries, refeed meals (with any note you add) and rest weeks, all logged and shown on the History tab (never on the timer screen).
- The badges you have earned.
The second is your profile and settings:
- Your confirmation that you are 18 or over, your answers to the screening questions and when you gave them, and the 48‑hour acknowledgement.
- A record of which stage cards you have read and whether you have opened the Sources screen, kept only so the Outcrop badge can be earned.
- Your settings, including Gentle Mode, Quiet Mode, reflections, timer style, notification preferences and quiet hours, iCloud sync and your preferred plan.
This is health-related information, which UK data protection law treats as special-category data. It is stored in the app's private storage on your iPhone and, for widgets and the Live Activity, in a shared container on the same phone that only Nesteia can read. It is not sent to us or to anyone else. The app sends none of it to iCloud unless you turn on iCloud sync, and then only the first list (section 3); your own iPhone backup may include all of it under Apple's terms.
3. iCloud sync, if you turn it on
iCloud sync is a Pro setting and is off by default. If you switch it on, the app stores your history (the first list in section 2) in the private database of your own iCloud account, using Apple's CloudKit, so that your other iPhones signed in to the same Apple Account can show the same history. That is your fasts, with the reason you gave, how you felt and any supervision confirmation recorded with each one; your weight entries, refeed meals and rest weeks; and your badges. Nothing else is synced. Your profile and settings (the second list) stay on the iPhone where you gave them: the 18+ confirmation, the screening answers and the acknowledgement, the record of what you have read, and every switch in Settings, the sync switch included. On another iPhone you confirm your age, answer the screening questions and set your switches again. That database belongs to you and is covered by Apple's privacy policy and the iCloud terms; we have no access to it, no key to it and no server of our own. Your health data never reaches us, with sync on or off.
You can switch sync off at any time in Settings; from the next time you open the app it stops writing to iCloud and keeps working from the copy on your phone. Sync stops if Pro ends; your data stays on the phone, and the copy in your iCloud is left as it is. "Delete everything" removes the iCloud copy as well as the local one, as long as the app was opened with sync on. Sync needs an iCloud account with iCloud Drive turned on; if it is unavailable, the app simply works on the device alone.
4. What we do not do
- No account or sign-in. The app never asks for your name, email or any identifier.
- No analytics, crash-reporting or advertising software is included in the app.
- No tracking across apps or websites, and no sale or sharing of data. iCloud sync, when you turn it on, shares nothing with us.
- No access to Apple Health, contacts, location or the camera.
The app's privacy manifest declares no collected data types and no tracking, and the App Privacy label set for its App Store listing reads "Data Not Collected".
5. Purchases
Nesteia Pro is sold only through Apple's App Store, once Nesteia is released there. Apple processes the payment and manages your subscription and any trial or refund under Apple's privacy policy. The app checks on your phone, using Apple's StoreKit, that a purchase is valid, so that it can unlock Pro; nothing about it is sent to us. Like every developer, we see only Apple's aggregate sales reports, which do not identify you. We never see your payment details, your name or your Apple account.
6. Notifications
If you allow notifications, the app schedules local reminders on your phone: when a stage begins, an hour before your planned end, when the planned fast is complete and, after an extended fast of a day or more, one note at 9:00 on each refeed morning. Stage changes, the final hour and the refeed reminders are each a switch in Settings; the note at your planned end always arrives. Inside your quiet hours a note arrives without a sound or a lit screen and waits in Notification Centre: it is delivered, not held back. Everything is created and delivered on the device, nothing is sent anywhere, and no notification service of ours is involved.
7. This website
This website is static. It sets no cookies and runs no analytics. If you choose light or dark with the switch in the header, your browser keeps that choice in its own local storage; it is never sent anywhere. The site is hosted on Cloudflare, which processes the technical details of each request, such as your IP address, to deliver the page and keep it secure. The fonts are served from this site too, so no third party is contacted to show a page. If you email us, we keep your message for as long as needed to answer it. If you use the "Email me at launch" link, your address is used once, to tell you Nesteia is out, and then deleted.
8. Your rights
Because your data never reaches us, you exercise your rights directly in the app:
- Access and portability: Settings, then Your data, produces either a CSV file of your fasts for a spreadsheet, or a JSON archive of everything the app holds (fasts, weight entries, refeed meals, rest weeks, badges, screening answers and settings) that you can keep, share or import on another phone.
- Erasure: Settings, then "Delete everything", removes all fasts, weight entries, refeed meals, rest weeks, screening answers, supervision confirmations, settings and badges in one step, including the iCloud copy when the app was opened with sync on. Deleting the app removes the copy on that phone.
- Withdrawing consent: you can change or delete your screening answers at any time in Settings, and switch iCloud sync off at any time.
If you believe we have handled information about you wrongly, email us first. You also have the right to complain to the Information Commissioner's Office at ico.org.uk.
9. Children
The app is for adults aged 18 and over. Its App Store age rating is 18+. We do not knowingly allow anyone under 18 to use it.
10. Changes
If a future version of the app changes how data is handled, we will update this policy, change the date at the top, and ask for your consent in the app before any new processing begins. Optional iCloud sync was added on 22 September 2026, off by default and yours to switch on or off, as section 3 describes. On 23 September 2026 section 3 was corrected to list exactly what sync stores in iCloud, section 2 was regrouped to match, and sections 4, 5 and 7 were made more precise about the App Store privacy label, how a purchase is checked and how this website is hosted; nothing about what the app does changed. Later on 23 September 2026 section 7 was updated: the website's fonts are now served from the site itself instead of Google Fonts, and it says how an address sent with the "Email me at launch" link is used.
11. Contact
Serhat Dereli, trading as Nesteia, Bromley, UK. serhatdereli@icloud.com.