Cycle Sync — Privacy Policy

Datenschutzerklärung · Information under Articles 13 and 14 GDPR

Cycle Sync was called Bloom until September 2026 · Last updated: 29 September 2026 · Impressum / Legal notice

1. Controller

Controller within the meaning of Article 4(7) GDPR:

Denis Golubev
Email: bloomcyclefitapp@gmail.com

Data protection officer: we have not appointed one. Cycle Sync is operated by an individual developer and does not process special category data on a large scale within the meaning of Article 37(1)(c) GDPR, nor does it meet the threshold in § 38 BDSG. If that changes, this section will be updated.

2. Health data and your explicit consent

Menstrual cycle information, symptoms and fitness metrics are data concerning health under Article 9(1) GDPR and receive special protection.

We process them only on the basis of your explicit consent under Article 9(2)(a) GDPR. There are two separate things to agree to, and you agree to them in two separate places:

• Keeping the data on your phone, and letting Cycle Sync use it there — you agree by granting the iOS permission you are asked for, and by entering the data yourself.
• Sending the derived summary in section 5 to an AI service outside the app — you agree by tapping “Agree & continue” on the “Your data stays yours.” step during setup, or by buying or restoring a Cycle Sync Premium subscription. Tapping “Continue without the AI coach” instead is a real choice, not a delay: your week is then built entirely on your iPhone and nothing in section 5 is sent. Cycle Sync records which of the two you did and when, so we can tell you if you ask.

You can withdraw either consent at any time, with effect for the future. Withdrawal does not affect the lawfulness of processing carried out beforehand. What to do depends on which one:

• If you subscribe: cancel Cycle Sync Premium in the App Store. Cancelling takes effect at the end of the period you have already paid for; from that moment the chat coach stops entirely, and your week is no longer rebuilt by the AI — Cycle Sync carries your existing plan forward on your iPhone instead. Nothing further is sent.
• If you are not a subscriber: turn off Account → Share a summary with the AI coach. From that moment nothing further is sent — your week is built entirely on your iPhone, and the plan you already have is kept as it is. The switch is there for the free plan; because the AI coach is what a Cycle Sync Premium subscription buys, subscribers stop the transfers by cancelling the subscription, as above.
• To withdraw completely, and delete the record of your consent: Account → Remove account. It erases your profile, cycle data, plan, runs and trusted contacts from the device, along with the record of the permission you gave, and takes you back to setup — where you are asked again, and can decline.

One thing that does not work, and we would rather say so than let you believe it. Revoking Cycle Sync's Apple Health access in iOS Settings does not stop this. It removes the three Health-derived figures listed in section 5 and nothing else — everything else in the summary comes from what you entered in Cycle Sync itself, and keeps being sent. An earlier version of this policy offered that as a way to withdraw. It wasn't one.

3. What stays on your device

The following is stored only in Cycle Sync's private storage on your iPhone: your name as you type it; your cycle information; daily check-ins (energy, mood, cramps, sleep, flow); your training plan and completed sessions; your run history including routes, distance, pace and heart rate; any trusted contact you pick for the safety feature; and your notification preferences. None of these entries is transmitted to us, and none of them is transmitted anywhere in the form you see it here.

There is one exception, and it is set out in full in section 5: to build your week and to answer you in the coach, Cycle Sync sends figures worked out from some of this — your predicted cycle phase, this week's sessions, and weekly totals and averages from your runs. Never the individual runs, your routes, or your heart rate. Your cycle entries and your symptom check-ins are never sent at all.

Because these entries stay on your phone, we cannot access, export or delete them for you — you control them directly. Deleting Cycle Sync removes all of it.

4. Processing activities, purposes and legal bases

Balancing test for the request counter (Art. 6(1)(f)): our interest is preventing automated abuse of a paid AI service. The data is a random identifier and a number, contains no content and no health data, and cannot be linked to you by us. We consider the impact on your rights minimal and that you would reasonably expect such a safeguard. You may object under Article 21 GDPR (see section 8).

Providing this data is neither legally nor contractually required. It is necessary to use the features described — without cycle data, Cycle Sync cannot adapt your plan — but you are free not to provide it and to use the app's free, non-adaptive features.

5. The AI coach — exactly what leaves your phone

Two things in Cycle Sync use an AI service outside the app: building your training week, and the coach you can chat to. The chat coach is part of Cycle Sync Premium. The AI week is built once for everyone during setup, and then weekly if you subscribe. Everything else Cycle Sync does — logging your check-ins, tracking your runs, and building and adjusting a plan on the phone itself — involves no network connection at all.

Nothing in this section is sent unless you have agreed to it (see section 2). If you tapped “Continue without the AI coach” during setup and never subscribed, none of it happens to you, and your week is built on your phone instead.

The two paths send different things, so here is each of them.

When Cycle Sync builds your week

• What you're training for: your goal, the fitness level you picked, how many days a week you want to run and which weekdays those are, and — if you're training for a race — the race distance and how many weeks away it is.
• Where you are in your cycle: your average cycle length, and the phase predicted for each of the seven days being built.
• This week as it stands: for each day, the session type, its length, and whether you have completed it.
• How your training is trending: for each of up to the last four weeks — the number of runs, the total distance, the average pace, and the average effort rating you gave those runs. Plus how many sessions this week's plan asks for, how many you have finished, and the effort rating from your most recent run. These are weekly totals and averages worked out on your phone; the individual runs behind them are not sent.
• Three figures worked out from your Apple Health running workouts over the last eight weeks: your average weekly distance, the distance of your longest single run, and your typical pace.
• One yes/no flag saying whether the app is already easing today's session because of how you said you feel.
• Whether you read distances in kilometres or in miles.

When you message the coach

• What you typed, word for word, and the conversation so far. This is the one field you fill in yourself, so it is worth knowing it goes across exactly as you wrote it.
• Where you are in your cycle: the predicted phase, which day of your cycle it is, how reliable that estimate is, how many days until your next period is expected, and whether it is already overdue.
• This week's plan: for each day, the weekday name, the session type and length, whether it's race day, whether it's today, and the one-line reason the day was adjusted — which may say that today's symptoms were strong enough to ease the session, but never what you logged.
• Whether you read distances in kilometres or in miles.

The check-ins you log never leave your phone. When you log energy, mood, cramps, sleep or flow on the check-in screen, those scores are read on your iPhone and nowhere else. If they are strong enough that the app eases today's session, the AI service is told only that today is being eased — never the scores, never a history of them. That decision is made on your device and needs no network connection.

There is one exception, and it is one you choose. If you describe how you feel to the coach in the chat, that message reaches the AI service like everything else you type there, and the coach may write a check-in from it. The scores it writes down are its own reading of your words — not the ones you logged — and they stay part of that conversation for as long as it goes on, the way the rest of the conversation does. Your logged check-ins are still never sent.

What we deliberately do not send

• Your name, and any device or advertising identifier.
• Your cycle entries, and the check-ins you log — no entry, no logged score, no history of them, on either path. (What you choose to tell the coach in the chat is a separate thing, covered above.)
• Individual runs. No route, no map, no GPS trace, no heart rate, no per-run record. What goes out about your running is the weekly totals and averages listed above, plus the distance of your longest single run.
• Raw Apple Health readings. Cycle Sync reads your running workouts, your VO₂ max and your year of birth on your phone. The VO₂ max and the year of birth are used only on the device and are never transmitted; from the workouts, only the three summary figures above are.
• Your location, and where you run.
• Any calendar date. Days are sent as weekday names and as distances in time — “four weeks ago”, “nine weeks until the race”, “eleven days until your period”. We won't lean on that as if it settled anything: no date is transmitted, but your cycle day, your average cycle length and the days until your next period would let whoever receives them work out roughly when your period falls. That is cycle data, we treat it as cycle data, and it is covered by the explicit consent in section 2.

What the request looks like it came from

It carries no name, no email, and no account. It is signed with an anonymous identifier — a random number created on your phone the first time this is used, which stays the same on that install so we can count requests and stop the service being abused. All we store against it is a per-day count. Those counts are deleted after 90 days. Neither what you send nor what the coach replies is stored on our servers at all.

Finding your race — a separate service, and the one that surprises people

During setup, if you're training for a race, you can tap “Find your race” and type a race name. What you type is sent to RunSignup, a race directory in the USA, as you type it — from the third letter onwards — so it can send back matching races. People often type a city or a country here, so treat it like any other search box: it is the one place in Cycle Sync where what you type reaches a company that is neither us nor the AI service.

The same search also downloads a public list of world marathons from RunDida. Nothing you typed goes there — Cycle Sync fetches the whole list and matches it on your phone — but, as with opening any website, RunDida's servers see that a request came from your internet connection.

Neither request contains anything about your cycle, your symptoms, your health or your training, and neither carries Cycle Sync's anonymous identifier. The search is optional — you can type your race name in yourself and skip it. It happens earlier in setup than the AI-coach agreement in section 2 and is independent of it, which is exactly why it is spelled out here.

Recipients (Art. 13(1)(e) GDPR)

Supabase and Anthropic act only on our instructions, under a data processing agreement. That agreement binds each of them to protect what we send to the same standard this policy commits us to — they may use it only to perform the service described here, may not use it for their own purposes, may not sell or share it onward, and must keep it under equivalent technical and organisational safeguards. Your messages are not used to train AI models. RunSignup and RunDida are not our processors — they are separate directories Cycle Sync looks races up in, and they handle what reaches them under their own privacy policies.

Transfer to a third country (Art. 44 ff. GDPR)

Generating the coach's reply, and building your week, involves transferring the summary in this section to Anthropic in the USA. The USA is not covered by a general adequacy decision. The transfer is safeguarded by Standard Contractual Clauses under Article 46(2)(c) GDPR, as incorporated into our data processing agreement with Anthropic.

The optional race search also sends what you type to RunSignup in the USA. There is no data processing agreement covering that one, because RunSignup is not acting for us — your search reaches it the way a search on any public website would. Nothing about your cycle, your health or your training is included, and you can skip the search entirely by typing your race name in yourself.

You should be aware that US authorities may in principle have access rights that do not correspond to the EU standard, and that enforcing your rights there may be more difficult. If you would rather nothing was transferred: decline at the “Your data stays yours.” step during setup, don't subscribe, and type your race name in rather than searching for it. Every other feature of Cycle Sync works entirely on your device.

6. Automated decision-making and profiling

How much of this is automated depends on which plan you are on, so here is both.

• On Cycle Sync Premium: your week is adapted automatically from your predicted cycle phase and from the check-ins you log — a hard day can be eased on a day you have said you feel rough — and the AI coach generates suggestions. This is automated processing, and adapting a plan to your data constitutes profiling in the sense of Article 4(4) GDPR.
• On the free plan: your week is not adapted from day to day. It is built from what you told us during setup — your goal, your level, the days you can run, and your race if you have one — and then, if you agreed in section 2, built once by the AI service, which is shown your predicted phases while it does so. From then on the same week is carried forward: your logged check-ins do not change it, and neither does where you are in your cycle. If you declined, no AI service is involved at any point and the week is worked out on your iPhone alone.

It does not produce legal effects or similarly significantly affect you within the meaning of Article 22(1) GDPR: the output is a training suggestion you are free to ignore, change or override at any time. Cycle Sync is not a medical device and gives no medical advice. If you describe symptoms suggesting a medical problem, the coach is instructed to tell you to contact a clinician rather than coach you through it.

7. Storage on your device (§ 25 TDDDG)

Cycle Sync stores information on your device solely to deliver the functions you have expressly requested. This is strictly necessary within the meaning of § 25(2) no. 2 TDDDG, so no separate consent banner is required. We do not use cookies, tracking pixels, SDK analytics or advertising identifiers.

8. Your rights

• Access (Art. 15), rectification (Art. 16), erasure (Art. 17), restriction (Art. 18) and data portability (Art. 20).
• Objection (Art. 21) to processing based on legitimate interest — here, the request counter.
• Withdraw consent (Art. 7(3)) at any time, with effect for the future.
• Complain to a supervisory authority (Art. 77) — in Germany, the data protection authority of your federal state, or ours: the Berliner Beauftragte für Datenschutz und Informationsfreiheit, Alt-Moabit 59–61, 10555 Berlin.

Practically: nearly all your data is on your device, so access and erasure are immediate via the app. For the anonymous request counter, email us — because the identifier is anonymous and not linked to you, we cannot find your record from your email address alone and will ask you to supply the identifier from the app. Where we genuinely cannot identify you, we may be unable to act on a request (Art. 11(2) GDPR).

9. Children

Cycle Sync is not directed at children. We do not knowingly process data from anyone under 16.

10. Security

Data on your device is protected by iOS. All transmission uses encrypted HTTPS/TLS. By keeping health data on your phone we have deliberately minimised what a breach of our servers could expose — there is very little there to take.

11. Changes

If this policy changes materially we will update the date above and note it in the app's release notes.