Privacy policy
What Tsugi collects, why, and what you can do about it.
01 Who we are
Tsugi (https://tsugideck.com) is run by Berzan Tas, a private individual, who is the data controller for the personal data described in this policy.
For anything about your data, email contact@tsugideck.com. We answer within one month.
Tsugi has not appointed a Data Protection Officer, because Article 37 GDPR does not require one for a service of this kind.
This policy is effective from 26 September 2026.
02 What data we collect
Our own database stores only the random user ID that Clerk assigns you. Your email and name stay with Clerk, our sign-in provider.
Account data (held by Clerk)
- Email address and username
- Password, stored by Clerk in hashed form. Tsugi never sees it.
- Name and profile picture, if you sign in with Google
- Sign-in sessions, with the IP address and browser details Clerk uses to keep them secure
Learning data (held on our server, linked to your user ID)
- Your decks, note types and notes, including everything you type into your flashcards
- Your review history: when you reviewed each card, the rating you gave and the resulting schedule
- Which official decks you added, and your daily limit for new cards
Files you upload
- Images (PNG, JPEG, WEBP) and audio (MP3) you attach to notes, up to 50 MB in total
- Anyone who has a file's link can open it without signing in. Links are long random addresses, and Tsugi never shows them to other users.
Technical data
- Your time zone, sent with each request so due cards match your day. We do not store it.
- Error logs on our server, which can contain your user ID and the name of a deck involved in an error
- Your light or dark theme choice, stored in your browser
Messages you send us
- Your email address and whatever you write when you contact us, for example to use your rights or report content
We use no analytics or advertising trackers.
03 Signing in with Google
If you choose "Continue with Google", Google shares your name, email address and profile picture with Clerk, which uses them to create your Tsugi account. We request only these basic scopes: openid, email and profile.
We use this data only to create your account, sign you in and show your email on your account page. We do not sell it, use it for advertising or share it beyond the providers in section 5.
Tsugi's use of information received from Google APIs adheres to the Google API Services User Data Policy.
Google handles your Google sign-in as a separate controller, under its own Privacy Policy.
04 Why we use your data
We use your data only to run Tsugi for you and to keep it secure, on the legal bases below.
| Purpose | Data | Legal basis (GDPR) |
|---|---|---|
| Create your account and sign you in | Account data | Art. 6(1)(b): performing our contract with you |
| Store your decks and schedule your reviews | Learning data, uploaded files, time zone | Art. 6(1)(b): performing our contract with you |
| Protect sign-up and sign-in from bots and abuse | IP address, browser details | Art. 6(1)(f): our legitimate interest in keeping Tsugi secure |
| Fix errors and keep the service running | Error logs | Art. 6(1)(f): our legitimate interest in a working service |
You need an email address or a Google account to use Tsugi. Everything else you add is up to you.
Tsugi schedules your reviews automatically with the FSRS algorithm. This only decides when a card comes back and has no legal or similarly significant effect on you. It is therefore not automated decision-making under Article 22 GDPR.
05 Who processes data for us
Four providers process data on our behalf, under data processing agreements. We do not sell your data or share it with anyone else.
| Provider | What they do for Tsugi | Data involved | Location |
|---|---|---|---|
| Clerk, Inc. | Accounts, sign-in and sign-in emails (verification codes, password reset) | Account data | USA |
| Cloudflare, Inc. | Hosts the website, stores uploaded files and encrypted backups, checks for bots at sign-up (Turnstile) | IP address, browser details, uploaded files, backups | Worldwide network, US company |
| OVH SAS | Hosts our application server and database | User ID, learning data, error logs | Canada (Beauharnois data centre), French company |
| Zoho Corporation B.V. | Hosts our email, including messages you send us | Your email address and messages | EU |
When you sign in with Google, Google acts as a separate controller (section 3).
06 Transfers outside the EU
Some of your data leaves the European Economic Area: our server is in Canada (run by OVH SAS, a French company), and Clerk and Cloudflare are US companies.
- Canada: the European Commission has found that Canada protects personal data adequately (Decision 2002/2/EC), so no further safeguards are needed.
- USA: transfers rely on the EU-US Data Privacy Framework where the provider is certified under it, and otherwise on the European Commission's Standard Contractual Clauses.
You can ask for a copy of these safeguards at contact@tsugideck.com.
07 How long we keep data
We keep your data while you have an account, and anything you delete is gone from our live systems within 8 days. That covers your account, decks, notes, uploaded files (including files never attached to a note) and error logs, which we keep for at most 7 days. One exception: when you delete a deck or a note, its review history stays until you delete your account, so your statistics remain complete. Your theme setting lives only in your browser (see section 8).
Emails you send us are kept only as long as we need them to handle your request.
Backups. We back up Tsugi every hour and keep backups for 30 days, only to recover from failures. The backups are encrypted and stored with Cloudflare. A copy of data you delete is removed from our backups within 35 days.
Deleting your account. You can delete your account yourself on the Account page. Deletion is immediate and cannot be undone.
- We erase your decks, notes, review history and uploaded files from our database and storage, and close your Clerk account.
- Copies in our backups are removed within 35 days.
- If another user has an identical file, for example from an official deck, their copy stays with them.
- Error logs that mention your user ID are deleted within 7 days.
08 Cookies and browser storage
Tsugi stores only what signing in and your own settings need, so it does not ask for cookie consent. There are no analytics or advertising cookies.
| What | Set by | Purpose | Kept for |
|---|---|---|---|
| Sign-in cookies | Clerk | Keep you signed in and protect your session | Until you sign out or the session expires |
tsugi-theme local storage entry | Tsugi | Remember your light or dark theme | Until you clear it |
During sign-up, Cloudflare Turnstile checks that you are not a bot, using your IP address and browser signals.
You can block or delete cookies in your browser settings. Signing in does not work without Clerk's cookies.
09 Your rights
To use any of these rights, email contact@tsugideck.com. We answer within one month.
- Access: get a copy of the data we hold about you.
- Rectification: have inaccurate data corrected.
- Erasure: delete your account yourself on the Account page, or ask us to do it.
- Restriction: ask us to limit how we use your data, for example while we check a complaint.
- Portability: receive the data you gave us in a machine-readable format.
- Objection: object to the processing we base on our legitimate interests (section 4).
You can also complain to a data protection authority. In Poland this is the President of the Personal Data Protection Office (Prezes Urzędu Ochrony Danych Osobowych), ul. Stawki 2, 00-193 Warsaw, uodo.gov.pl. You may instead complain in the EU country where you live or work.
10 Age, security and changes
Minimum age. You must be at least 16 years old to use Tsugi. If we learn that a younger person has an account, we delete it.
Security. All traffic to Tsugi is encrypted with HTTPS. Your learning data is visible only to your account, and our server accepts requests only with a valid sign-in token. Uploaded files are the one exception, described in section 2: anyone with a file's link can open it.
Changes. When we change this policy, we update the effective date in section 1. If a change is significant, we tell you before it takes effect.