Privacy Policy

1. Who is responsible

The controller of your personal data is Andrii Boiko (sole proprietor (FOP) registered in Ukraine), Kyiv, Ukraine (“we”, “Duoday”).

Address: Harmatna St. 51, 03058. Phone: +380992876865. Email: andrew@andrewboyko.name.

2. The short version

• Everything you and your partner write in Duoday (names, dates, questions, answers, events) is end-to-end encrypted on your devices. We cannot read it.
• There are no ads, no trackers, no analytics or advertising SDKs, and no account.
• You can leave your pair and delete your data from our server at any time, inside the app.
• You must be at least 13 years old.

3. What stays on your device

Your relationship start date, names, colors, events, theme and settings are stored on your phone. Counters, widgets and watch complications are calculated on the device and do not need the internet. Without a partner and without a network, Duoday works fully on its own.

4. What our server stores

To connect two phones, our server stores only:

• a random device ID and a hash of its secret (we never store the secret itself), the platform (iOS, Android or watch) and your language setting;
• a random pair ID, which of the two member slots (0 or 1) each device holds, invite codes (valid for 7 days, single use) and when they were created;
• your push notification token, only if you allow notifications;
• the date until which Duoday Plus is active for your pair, and a purchase identifier (the original transaction ID or purchase token) used to check that a purchase is genuine and is not reused;
• encrypted records: for each record its type, an identifier, a key such as the day and question number (for example q:20261021-P007), who wrote it, version numbers, timestamps and the size of the encrypted data;
• if you write to support: your email address, your optional name and your message.

What we cannot see: names, dates, the text of your answers, your events and the encryption key. That content is stored only as ciphertext (AES-256-GCM). Metadata stays visible to us: that two devices are paired, when records are written and how large they are. Because records are filed under a day and a question number, we could in principle tell which standard question of the question bank was shown on a given day, but never what you answered.

5. How the encryption key works

The key is generated on the phone of the person who creates the pair. It reaches the partner only inside the invite link, after the # sign. Browsers and apps never send that part to a server, and the web page that opens the link only hands it to the app on your device. Anyone who has the link can read your shared data, so send it to your partner through a private channel only.

The key is kept in the iOS Keychain or the Android Keystore. If you lose it (for example after reinstalling), we cannot recover your shared data because we do not have the key; your partner can send you the link again.

6. Logs

Our web server and API write technical logs (time, requested address, IP address, status code, browser or app identifier) to keep the service secure and working. We keep these logs for at most 14 days. Application logs contain no personal data: device identifiers are shortened to 8 characters and no content is logged. IP addresses are also held briefly in memory for rate limiting.

7. Why we process data

• to provide the app and sync between your devices (contract, Art. 6(1)(b) GDPR);
• to keep the service secure, prevent abuse and fix errors (legitimate interests, Art. 6(1)(f) GDPR);
• to answer your messages (contract or legitimate interests);
• to meet accounting or tax duties for purchases, where they apply (legal obligation, Art. 6(1)(c) GDPR).

We do not profile you and we do not make automated decisions about you.

8. Purchases

Purchases are handled by Apple (App Store) or Google (Google Play). We do not see your payment details or your Apple ID or Google account. Apple or Google provide a signed receipt or purchase token that we check; we use it only to switch Duoday Plus on for your pair and to stop the same purchase being used twice.

9. Who receives data

We do not sell data and we do not share it for advertising. Recipients are limited to:

• our hosting provider (Hosting Ukraine LTD, Kyiv, Ukraine), which runs the server;
• Apple (APNs) and Google (Firebase Cloud Messaging), to deliver push notifications that contain only a neutral text and never your content;
• Apple and Google, for purchase verification as described above;
• authorities, if the law requires it.

Data may be processed outside your country, including outside the EU/EEA (for example by Apple and Google). Where required, such transfers rely on the safeguards those companies offer, such as the EU–US Data Privacy Framework or standard contractual clauses.

10. How long we keep data and how to delete it

• In the app, Leave pair and delete my data removes the records you wrote, your push token and your membership from our server immediately. If you were the last member, the whole pair is deleted.
• Records deleted in the app remain as empty markers (without content) for up to 180 days so that your partner's phone can learn about the deletion.
• Server backups are rotated daily and kept for 7 days, so deleted data disappears from backups within 7 days.
• Devices that never joined a pair are removed after 180 days of inactivity.
• Support messages are kept for up to 12 months.
• Logs are kept for at most 14 days.

Your partner keeps the copies already stored on their own phone; we cannot remove them. You can export your data in the app (Me, Export our data, as JSON or PDF) and delete everything local by deleting the app.

11. Your rights

Under the GDPR and similar laws you may ask for access to your data, correction, deletion, restriction and portability, and you may object to processing. Most of this you can do yourself in the app (export and delete). For anything else write to andrew@andrewboyko.name; we answer within 30 days. Because we hold no accounts or names, we may ask you for details from your app to find your records. You also have the right to complain to your data protection authority.

12. Children

Duoday is for people aged 13 and over. We do not knowingly collect data from children under 13. If you believe a child has used Duoday, contact us and we will delete the data.

13. Security

Traffic is protected with TLS. Content is end-to-end encrypted with AES-256-GCM. Device secrets are stored only as hashes. No system is perfectly secure, but we collect as little as we can, so there is little to lose.

14. Changes

If we change this policy in a meaningful way, we will update the date above and tell you in the app about significant changes.

15. Contact and trader details

Andrii Boiko (sole proprietor (FOP) registered in Ukraine), Harmatna St. 51, 03058, Kyiv, Ukraine. Phone: +380992876865. Email: andrew@andrewboyko.name. Registration: entered in the Unified State Register of Legal Entities, Individual Entrepreneurs and Public Organisations of Ukraine.

These are also the contact details of the trader under the EU Digital Services Act.