ShadowTube Privacy Policy

Effective date: 11 October 2026

This policy explains what personal data the ShadowTube iOS app and its server process, why, who else receives it, how long it is kept and what your rights are.

1. Who we are

ShadowTube is provided by markttor UG (haftungsbeschränkt), Tempelhofer Weg 59, 12347 Berlin, Germany (“we”, “us”). We are the controller responsible for your personal data under the EU General Data Protection Regulation (GDPR). You can reach us by email at support@shadowtube.app.

2. What data we collect and why

We process the data below to provide ShadowTube to you, that is, to perform our agreement with you (Art. 6(1)(b) GDPR), unless a different reason is given.

• Account. Your email address and password. You sign up and sign in directly with Supabase, our account provider, which stores your email address and a hash of your password. Our own server never receives your password. Your account has a random account ID that links all the data below.
• Sign in with Apple (optional). If you sign in with Apple instead, Apple confirms your Apple ID to Supabase and shares the email address you choose to share (your own, or a private relay address from Apple’s “Hide My Email”) and, the first time and only if you share it, your name, which is kept with your account. So that we can end ShadowTube’s connection to your Apple ID when you delete your account, our server exchanges a one-time code from the app with Apple for a token and stores that token encrypted.
• Settings. Your app preferences: which speech recognition and voice service to use, the voice, the playback speed, the language you are learning and your native language.
• Library and progress. Which YouTube videos you add or open, when you added them, and where you stopped watching. Together this is your learning history in ShadowTube.
• Voice recordings and practice results. When you practise speaking: your recording, the text recognised from it, word timings and recognition confidence, and your score for the sentence. See “Voice recordings” below.
• Your own API keys (optional). If you add your own OpenRouter or ElevenLabs API key, we check it with that provider, store it encrypted and show only its last four characters in the app.
• Subscription. If you buy ShadowTube Pro: your plan and when it ends, and for each App Store transaction its transaction IDs, the product and the purchase, expiry and revocation dates. Apple handles the payment; we do not store your payment details, the price or your Apple ID. So that a purchase can be matched to your account, the app passes your account ID to Apple with the purchase.
• Usage counts. To apply the limits of your plan, we count per day or per month how many limited actions you use, such as practice scorings, newly generated computer voices and added videos, and we record whether and when you used the free plan’s one free video.
• Videos you add. When you add a video, open one that is not prepared yet, retry a video, or open a video’s subtitles in a native language they have not been translated into yet, our server prepares what is missing (see “YouTube” and “Third-party services”) and records your account ID with that processing job and, if you are the first to add or open the video, with the video. The video’s public details, transcript and translations are stored once and shared with everyone who uses the same video; they describe the video, not you.
• Server logs. When the app contacts our server, including when it loads the video player page, the server logs your IP address, the address requested (which can include a YouTube video ID or words you looked up), the request headers your device sends (such as its user agent, which names the app and iOS version, and its preferred language; sign-in tokens are not logged), the time and the result. Our application logs also record your account ID next to some actions, such as opening or adding a video, requesting translations, reaching a plan limit, App Store purchases (with their transaction IDs) and account deletion. They do not contain your email address, API keys, recordings or recognised text. We use logs to operate, secure and fix the service, which is our legitimate interest (Art. 6(1)(f) GDPR).

ShadowTube contains no advertising, analytics or crash-reporting tools and does not use your device’s advertising identifier. YouTube’s own player, which the app uses to play videos, is described under “YouTube”.

If you test ShadowTube through Apple’s TestFlight, Apple shares with us your name and email address (if we invited you by email), information about your installs and sessions, crash reports and any feedback you send, as described in TestFlight’s terms. We use this only to test and fix the app.

On your device

The app keeps some data on your device: your sign-in session (in the iOS Keychain), your settings, copies of your own practice recordings, cached audio and thumbnails, and a note that your account (account ID and email address) has finished the in-app tour. Recordings kept by the app can be included in your iPhone or iCloud backups. Signing out, which also happens when you delete your account, removes the sign-in session; iOS can keep it after you delete the app, so sign out first. The rest is not removed when you sign out or delete your account; deleting the app removes it.

3. Voice recordings

• The app uses the microphone only for shadowing practice, never in the background. iOS asks for your permission the first time you record, and you can withdraw it at any time in the iOS Settings.
• In shadow mode, the video stops after each sentence so you can repeat it. The microphone then switches on by itself and stops shortly after you stop speaking, or after about 8 seconds if you say nothing. Outside shadow mode, recording happens only when you choose to practise a sentence. The microphone then switches on by itself in the “On the video” style; in the side panel, you tap to record.
• Each recording is uploaded to our server, which sends it to a speech recognition service (see “Third-party services”) to turn it into text, and then compares that text with the sentence to score you word by word.
• We store your recordings (as 16 kHz mono audio, at most 60 seconds each) on our server together with the recognised text and your score, so you can listen to them again and follow your progress. Only your own account can download them. Our server uses your recordings only to score your practice and to play them back to you. If scoring fails, the server deletes the recording.
• Recordings and practice results are kept until you delete your account. Removing a video from your library does not delete its recordings, and single recordings cannot currently be deleted in the app.

4. Third-party services

We use these service providers:

• Supabase (sign-in and database) receives your email address and password directly from the app, together with your IP address and your device’s user agent when you sign up, sign in or out, or your session is refreshed. It stores the account data described above and records sign-ins and other account events in its own security logs. Our database is hosted in the EU, in the Ireland region of Amazon Web Services.
• Hetzner Online GmbH (server hosting) runs our server, which stores the voice recordings and the server logs, in Germany.
• Namecheap, Inc. (domain registrar) answers the DNS lookups for shadowtube.app, our server’s web address, and forwards email sent to our support address. Test versions of the app made before October 2026 use an address at sslip.io instead. These lookups normally come from the DNS resolver of your network or internet provider rather than from your device.
• OpenRouter (speech recognition and computer voices) receives your voice recordings to recognise your speech, the audio of YouTube videos to create transcripts, and texts to be read aloud. OpenRouter passes these on to Microsoft’s AI models, which run on Microsoft Azure. Your email address and account ID are not sent.
• ElevenLabs (speech recognition and computer voices) receives your voice recordings and texts to be read aloud for you only if you add your own ElevenLabs API key. It can also receive the audio of YouTube videos, or a video’s YouTube link, to create transcripts. Your email address and account ID are not sent.
• Anthropic (Claude AI) creates the translations and word explanations of video transcripts. It receives only a video’s public title and transcript text, never data about you.
• Apple (App Store) processes purchases and subscriptions and informs our server when a subscription changes. If you use Sign in with Apple, Apple signs you in, our server receives the token described under “Sign in with Apple” from Apple, and when you delete your account our server asks Apple to revoke it. Apple’s handling of your purchase and your Apple ID is governed by Apple’s privacy policy.
• Google (YouTube): see “YouTube” below.
• Cloudflare: our server downloads YouTube audio through Cloudflare’s WARP network. These downloads contain no data about you.

If you add your own OpenRouter or ElevenLabs API key, our server uses it only for your own requests. Those requests run under your account with that provider, so its terms and privacy policy also apply.

Some of these providers may process data outside the European Union, including in the United States. How long they keep the data they receive is governed by their own terms and policies.

5. YouTube

ShadowTube uses YouTube API Services. Videos play in YouTube’s own embedded player inside the app, loaded from www.youtube.com (not YouTube’s privacy-enhanced mode). When the player loads or plays a video, your device connects directly to YouTube (Google), which receives your IP address, which video you watch and how you use the player, and can store cookies or similar data on your device. The app keeps this data between launches and does not clear it when you sign out or delete your account; deleting the app removes it.

The app also loads video thumbnails directly from Google’s servers and, when you paste a YouTube link, asks YouTube directly for the video’s title and channel. Our server fetches the details and audio of the videos users add or open from YouTube to create transcripts; these requests identify only the video, nothing about you.

Google’s processing is governed by the Google Privacy Policy. Watching videos is also subject to the YouTube Terms of Service.

6. Where your data is stored and how we protect it

• Our database is hosted by Supabase in the EU (Amazon Web Services, Ireland). Our server, which stores voice recordings and logs, is hosted by Hetzner Online GmbH in Germany.
• Connections from the app to our server and to Supabase, and from our server to our service providers, are encrypted (HTTPS).
• The app and other users cannot read the database directly.
• Your API keys are encrypted with a key that is kept only on our server, so the database holds only the encrypted keys and their last four characters.
• Our server’s firewall lets through only web traffic and administrator access.

7. How long we keep data

• Your account data (settings, library and playback positions, practice results and recordings, API keys and usage counts) is kept until you delete your account. We do not delete it automatically after a fixed period.
• Server logs are not deleted when you delete your account. The web server’s access log starts a new file when the current one reaches 10 MB, so how long an entry stays depends on traffic; it keeps at most five older, compressed files and removes files older than 90 days. Our application’s logs, which also record your IP address and the address requested, are kept in the server’s system journal, which deletes its oldest entries when it reaches its size limit and has no fixed time limit.
• After you delete your account we keep: records of App Store transactions (transaction IDs, product and dates), no longer linked to your account; your former account ID in records of video processing and as the account that first added or opened a shared video, without any email address; and the shared video data (transcripts, translations and audio), which is not about you.
• Copies of deleted database data may remain in Supabase’s backups until those backups expire. Entries about your account in Supabase’s security logs, which can include your email address and IP address, may also remain.
• Deleting the app removes the data the app stores on your device, except the sign-in session in the iOS Keychain, which iOS can keep after the app is deleted. Sign out before deleting the app to remove it (see “On your device”).

8. Deleting your account

You can delete your account in the app under Settings → Delete account. This deletes right away: your login (email address and password, or your Sign in with Apple link, name and token), your settings, API keys, library and playback positions, practice results, the voice recordings stored on our server and your usage counts. If you signed in with Apple, our server first asks Apple to revoke ShadowTube’s access to your Apple ID; you can also end it yourself in your iPhone’s Settings under your Apple ID → Sign in with Apple. What we keep afterwards is listed under “How long we keep data”. Data that service providers have already received is governed by their own policies (see “Third-party services”).

Deleting your account does not cancel a ShadowTube Pro subscription; cancel it in your Apple account’s subscription settings. It signs you out, but it does not remove the other data the app stores on your device; delete the app to remove it.

If you cannot use the app, contact us (see “Who we are”) and ask us to delete your account.

9. Your rights

Under the GDPR you have the right to:

• access the personal data we hold about you and receive a copy (Art. 15);
• have incorrect data corrected (Art. 16);
• have your data deleted (Art. 17);
• have the processing of your data restricted (Art. 18);
• receive the data you gave us in a common, machine-readable format (Art. 20);
• object to processing based on our legitimate interests (Art. 21).

To use these rights, contact us. You can reach us by email at support@shadowtube.app.

You also have the right to lodge a complaint with a data protection supervisory authority, in particular in the EU member state where you live or work or where you believe your rights were infringed (Art. 77 GDPR).

10. Children

ShadowTube is not designed for children and does not ask for your age. If you are under 16, please use ShadowTube only with the permission of a parent or guardian. If you believe a child has given us personal data without that permission, contact us so we can delete it.

11. Changes to this policy

We may update this policy when ShadowTube or the services we use change. We will publish the new version on this page and update the effective date at the top.