Privacy Policy
Cellopedia Practice Room
Kozlov Cello Studio LLC, Maryland, USA
Last updated: 11 September 2026
Effective: 11 September 2026
The short version
I built this app to help adult cellists practise better. I collect as little about you as I can. I do not sell your information, I do not share it for advertising, and your recordings never leave your own device - I never receive them.
You can delete your account and everything in it at any time, from your account page, without asking me.
Questions, requests, or complaints: hello@cellopedia.org.
The rest of this document says all of that precisely, because some of you live in places whose laws require precision, and because you deserve it either way.
1. Who is responsible for your data
Kozlov Cello Studio LLC (“I”, “me”, “the business”) operates Cellopedia Practice Room at practice.cellopedia.org. The business is registered in Maryland, United States.
For the purposes of the UK and EU General Data Protection Regulation, I am the data controller for the information described here.
Contact for all privacy matters: hello@cellopedia.org.
I do not have a Data Protection Officer. At this size the law does not require one, and adding a layer between you and me would not serve you.
2. Who may use this service
You must be 18 or older to create an account. This service is not directed to children, and I do not knowingly collect personal information from anyone under 18. If you believe a minor has created an account, contact us at hello@cellopedia.org and I will delete it promptly.
The free practice tools - metronome, tuner, drone, and slow-downer - work with no account and collect nothing about you.
3. What I collect, why, and on what legal basis
The table below covers everything. “Legal basis” is a GDPR concept; if you are not in the UK or EU it does not affect your rights here, all of which I offer to everyone.
| What | Why | Legal basis |
|---|---|---|
| Email address | To sign you in - there is no password - and to contact you about your account | Performance of a contract |
| Newsletter choice and its timestamp | To honour your choice and to show when you made it | Consent, and legal obligation to evidence it |
| Practice sessions: your written goal, the obstacle you named, passage labels, reflections | To show your own practice history back to you | Performance of a contract |
| Session measurements: timers, repetition counts, tempo settings | The same | Performance of a contract |
| Feedback you choose to send: bug reports and suggestions, and the piece they concern | So I can read them, fix what they report, and follow up if needed | Legitimate interests |
| A reference video link you save for a piece | To show you the same video next time | Performance of a contract |
| Stripe customer and subscription identifiers, plan and status | To run your subscription | Performance of a contract |
| Billing records: invoices with the name, email and address you gave | Tax and accounting law requires me to keep them | Legal obligation |
| Your agreement to the auto-renewal terms, what you were shown, and when | To evidence that the terms were disclosed and agreed before any charge | Legal obligation |
| Server logs, including IP addresses | Security, and keeping the service running | Legitimate interests |
Audio recordings of your playing, and everything your microphone hears, are deliberately absent from this table: they never leave your device. Section 4 explains.
I never see or store your card number. Stripe handles payment details directly.
I do not use automated decision-making or profiling that produces legal or similarly significant effects.
4. Your recordings and your microphone
Your recordings are audio of you playing. I want to be direct about them.
Your recordings never leave your device. They are stored only in your own browser, on the device you recorded them with. They are not uploaded, not synced, and not stored on my servers. I could not listen to them if I wanted to - I do not have them.
Two consequences worth stating plainly:
- A recording exists only on the device that made it. If you want a take on another device, or want to keep it safely, use the download button - every take has one.
- Clearing your browser’s site data deletes your recordings, and browsers may clear rarely-used site data on their own. Download the takes that matter to you. The app says this in the recording library too, because it is the kind of thing that should not live only in a policy.
The microphone. The tuner and the mic test listen through your microphone while you use them. That audio is analysed in your browser in the moment - to show you a pitch or a level - and is not stored, not sent anywhere, and never reaches me. Your browser asks for microphone permission the first time a tool needs it, and you can withdraw that permission in your browser’s settings at any time.
5. Who else handles your data
These companies process data on my instructions, under contract, and may not use it for their own purposes:
| Who | What they handle | Where |
|---|---|---|
| Supabase | Your account and practice sessions | United States |
| Stripe | Payment processing and billing records | United States and worldwide |
| Vercel | Hosting for the app | United States |
| Mailchimp | The newsletter, if you opt in, and the launch waiting list | United States |
| Resend | Sending account and billing email | United States |
YouTube videos are embedded on some piece pages. When one loads, YouTube may set cookies and receive your IP address, under Google’s privacy policy rather than mine. Nothing is sent to YouTube until a video is loaded.
International transfers. If you are in the UK or EU, your data is processed in the United States. Each of the companies above relies on the European Commission’s Standard Contractual Clauses, or an equivalent approved mechanism, for that transfer. You may ask me for details.
6. What I do not do
- I do not sell your personal information, and I have not in the past twelve months.
- I do not share it for cross-context behavioural advertising.
- I do not use it to train machine learning models.
- I do not send marketing email unless you asked for it.
Under California law, the terms “sell” and “share” have specific technical meanings. Neither applies to anything I do. There is no “Do Not Sell or Share My Personal Information” link on this site because there is nothing to opt out of.
Email about your account - a sign-in code, a receipt, a notice that your trial is ending - is not marketing. You will receive it whether or not you subscribed to the newsletter, because it is part of the service.
7. How long I keep things
| What | How long |
|---|---|
| Your account and practice history | Until you delete them |
| Feedback and saved reference links | Until you delete your account, then deleted with it |
| Your recordings | Never held by me - they exist only on your own device, until you delete them or your browser's data is cleared |
| Newsletter consent records | While your account exists, then deleted with it |
| Billing records and invoices | Retained by Stripe and by me for the period tax and accounting law requires, currently up to seven years, and used for nothing else |
| Server logs | Retained by my hosting provider for a short period, typically about thirty days |
| Backups | Overwritten on a rolling basis; deleted data disappears from backups within about thirty days |
Section 9 explains what survives account deletion, and why.
8. Your rights
Whoever you are and wherever you live, you can:
- Know what I hold about you, the categories, the sources, why I have it, and who else handles it. Much of it is in this document; contact us at hello@cellopedia.org for the rest.
- Get a copy, in a portable format.
- Correct anything that is wrong.
- Delete it. You do not need to ask - there is a delete option on your account page. See section 9.
- Restrict or object to processing, including processing based on legitimate interests.
- Withdraw consent to the newsletter at any time, from your account page or any newsletter email. Withdrawing does not affect what was done before.
- Not be discriminated against for exercising any of these. The service works the same either way.
How to ask. Contact us at hello@cellopedia.org. I will confirm within ten business days and answer within thirty days - or within one month for UK and EU requests, extendable by two further months for complex requests, in which case I will tell you why.
Verification. I will ask you to write from the email address on the account. That is normally enough. For deletion I may ask you to confirm the request a second time, because deletion cannot be undone.
Authorised agents. If someone makes a request on your behalf, I will ask for written proof that you authorised them, and may still ask you to confirm directly.
Complaints. Contact us at hello@cellopedia.org first. If you are not satisfied: in the UK, the Information Commissioner’s Office; in the EU, your national supervisory authority; in California, the California Privacy Protection Agency or the Attorney General.
9. Deleting your account
You can delete your account yourself, from your account page. It is permanent.
When you do:
- Your practice sessions and account details are removed from my live database at once, and age out of rolling backups within about thirty days (section 7).
- The local copies on the device you delete from are cleared, recordings included.
- Any active paid subscription is set to end when the current period does, and is never charged again. Nothing is refunded, and because the account is gone the remaining time cannot be used - to use what you have paid for, cancel first and delete when the period ends. If you are on a free trial, the trial is cancelled at once and the card on file is never charged.
- Your name, email and address are removed from your Stripe customer record.
What survives, and why. Invoices for payments already made remain in Stripe. Tax and accounting law requires records of transactions, and under both GDPR and California law that obligation takes precedence over erasure. Those invoices contain the billing name, email and address you gave at the time. I keep them for the statutory period and use them for nothing else.
The record of your agreement to the auto-renewal terms - what you were shown, what you ticked, and when - survives for the same reason and for the same period: it evidences consent to charges already made, and a dispute can arrive months after deletion. It contains no name, email or address; after deletion it is tied only to an internal identifier that no longer points to any account. I use it for nothing else.
Recordings on your other devices are not touched - they never passed through me, so deleting your account cannot reach them. Delete them from each device yourself if you want them gone. Practice sessions cached on other devices clear themselves when each next connects.
10. Security
Sign-in uses a code sent to your email rather than a password, so there is no password of yours for anyone to steal from me. Data is encrypted in transit. Recordings never reach my servers, so there are no recording files here to breach. Database access is restricted so that your data is reachable only by your account.
No system is perfectly secure and I will not pretend otherwise. If a breach occurs that is likely to affect your rights, I will notify you and the relevant authorities within the time the law requires - 72 hours to a supervisory authority under GDPR.
11. Cookies and what is stored on your device
No advertising or tracking cookies. No third-party analytics.
The app stores the following on your device because it cannot work otherwise:
| What | Purpose |
|---|---|
| Your sign-in session | To keep you signed in |
| Your practice sessions and recordings | So the app works offline and your takes are not lost |
| Display and sound preferences | To remember your choices |
| A copy of the piece index and cached music files | So the library works offline |
| A marker of which account this device last synced | To keep one person's data from appearing under another's account on a shared device |
None of it is used to track you, and none is shared.
Embedded YouTube videos may set their own cookies when a video loads, as described in section 5.
Do Not Track. Browsers send this signal inconsistently and there is no agreed standard for honouring it. Since I do no tracking, there is nothing for it to disable.
12. Changes
If I change this policy in a way that meaningfully affects you, I will tell you by email or in the app before it takes effect. The dates at the top show when it was last revised.
13. Contact
Kozlov Cello Studio LLC
Maryland, United States
hello@cellopedia.org