Privacy Policy
Sentinz helps you learn Dutch vocabulary. To do that it stores what you are learning, listens while you speak, and reads photographs you choose to take. This page explains exactly what that means.
Who is responsible
Sentinz is a trade name of Amstel Serene Real Estate B.V., registered with the Dutch Chamber of Commerce (KvK) under number 93294441, at Zilverschoonlaan 4, 1187 EC Amstelveen, the Netherlands.
Amstel Serene Real Estate B.V. is the controller for the personal data described here. You can reach us at info@sentinz.com.
What we collect, and why
| Data | Why | Kept? |
|---|---|---|
| Your account — email address, a password if you set one, and your name if you give it to us or Apple or Google share it | To create your account, sign you in and address you by name. Passwords are stored only as a cryptographic hash — we never see them. | Until you delete your account |
| Your learning data — which words you study, review history, scheduling state, your level and your target | This is the app. Spaced repetition works by remembering how you performed and when. | Until you delete your account |
| Sentences you speak — the text of what you said | To judge whether you used a word correctly, and to show you your own attempts later. | See retention below |
| Conversations with the voice tutor — the text of what you and the tutor said, with timings and the verdicts on your sentences | So the tutor can follow the conversation, and so we can find and fix what went wrong in one. | 14 days, then the text is deleted automatically. Nothing is kept of a conversation in which we detected a crisis |
| Voice recordings | Converted to text so your sentence can be checked, and scored for pronunciation when you ask for that. | Not stored. Discarded once transcribed or scored |
| Photographs you take of letters, signs or menus | To find the Dutch words in them and turn those into cards. | Not stored. We keep the words, and with each word the one sentence of the letter it came from, with personal numbers taken out |
| Feedback you send us — your score, your comments, and your email if you want a reply | To improve the app, and to answer you. | Until you delete your account |
| Your subscription status — which plan, and until when | To unlock what you paid for. Payment itself is handled by Apple; we never see your card. | Until you delete your account |
| Time with the tutor — how many minutes a day you spent with the voice tutor, in course lessons with the tutor and in chats with Laura | To count tutor time against your plan, and to show you your usage and your activity calendar. Only the minutes are kept, never what was said. | Until you delete your account |
| Chat reports — a short summary of each chat with Laura or Daan: the date, the topic, how long you talked, whether you reached the goal, your scores, a few of your sentences with their corrections, and the words you used | To show you your past chats, and to bring back the corrections you have not mastered yet. The summary is all that is kept, never the whole conversation. | Your sentences: 90 days. The rest of the summary: until you delete the chat or your account |
| Words to practise saying — the Dutch words you said that scored below the pass mark, with their scores and where in the app you said them; your stars per sound and the days you practised | To build your list of words to polish in Pronunciation, and to take a word off once you say it well. Never the recording, and never the sentence the word was in. | Until you delete your account; a word you take off the list yourself is deleted at once |
| Usage counts and server logs — how many requests your account made today; technical logs of the voice tutor, which record what happened in a lesson but not what was said | To stop abuse of the paid AI features, keep the service running and diagnose faults. | Usage counts 30 days; server logs 14 days |
| What you agreed to — that you confirmed your age, accepted the Terms, gave the AI permission and consented to scanning, each with its version, the date and time, and the App Store country your minimum age came from; and when you took something back | So we can show what you agreed to and when, as the law asks of us, and so the app asks again when something changes. | Until you delete your account |
| Technical data — your IP address, the type of phone and the versions of iOS and the app, when you signed in, and Apple’s numbers for your purchases | To deliver the app and its updates, keep you signed in, protect the service against abuse, and match a purchase to your account. | IP addresses in our server logs 14 days; sign-in times and purchase numbers until you delete your account |
Please read this part
Two features process material that can be sensitive, so they are worth understanding before you use them.
Sentences you invent are about your own life. When the app asks you to use a word in a sentence, people naturally talk about their family, their health, their work or their appointments. That text is stored against your account so you can see your own history. Say only what you are comfortable storing.
Photographs of official letters contain other people's data too. A letter from the gemeente or the Belastingdienst may carry your name, address, BSN or details about your health or benefits. Before your first scan the app explains what happens and asks for your explicit consent, which you can take back at any time in Settings → Privacy & data. The image is sent for processing and then discarded — we never store it — but it is sent. We keep the vocabulary words, and with each word the sentence of the letter it appeared in, so you can see it in context. Before that sentence is stored, numbers such as a BSN, IBAN or phone number, postcodes and email addresses are taken out, and the AI is asked to leave out names and addresses. It can still miss a detail, so look at the card; deleting the card deletes the sentence. Scan only letters that are yours to share.
Conversations with the voice tutor are kept for 14 days. What you say to the tutor, or to Laura or Daan, is stored as text, together with their replies, so that when a lesson goes wrong we can see why. The text is deleted automatically after 14 days, and at once if you delete your account. If what you say suggests you may be in danger, the app gives you a helpline, and no text of that conversation is kept.
In a chat with Laura or Daan you may invent anything. It is practice: a made-up name, job or family works just as well, and you never need to tell them anything private. They do not remember what you said from one chat to the next.
What to leave out. In any conversation with the tutor, Laura or Daan, please don’t share details about your health, religion, political views or sex life, your ID, BSN or bank numbers, or private details about other people, such as a friend’s illness or a colleague’s full name. You never need them to practise; a made-up answer works just as well. If you share them anyway, they are treated like everything else you say: kept only as long as this policy says for that kind of data, and never used to train AI.
Our legal basis
We process this data to perform our contract with you — to provide the app you signed up for (Article 6(1)(b) GDPR). That includes sending your speech, your sentences and the words you add to the AI services listed below: checking your Dutch and running the tutor is the service. Counting your time with the tutor is part of that contract too: your plan includes a set amount of it. So is keeping a report of each chat with Laura or Daan, just as the app keeps your learning history: looking back at a chat and practising its corrections again is part of how the app teaches.
The “Before you start” screen. Before the first AI feature, the app shows which service receives what, and asks you to confirm your age, accept the Terms and agree. That screen makes sure nothing goes to an AI service before you know where it goes (Apple asks every app to do this). It is a permission, not our legal basis: the basis stays our contract with you. If you take the permission back (Settings → Privacy & data), the AI features stop, and because the app is built on them, you are signed out until you agree again.
Scanning letters is different. It is optional — you can always type a word instead — and a letter can contain details about your health, which the GDPR treats as a special category. So we scan only with your explicit consent (Articles 6(1)(a) and 9(2)(a)), asked on its own screen before your first scan and recorded. You can withdraw it at any time; that stops new scans and does not undo the cards you already made.
Keeping the text of tutor conversations for 14 days, counting requests and keeping server logs rest on our legitimate interest (Article 6(1)(f)) in keeping the service secure, working and improving. Conversation text and server logs are kept no longer than 14 days and request counts no longer than 30, and they are seen only by the people who run Sentinz, who sign in with two-step verification. You can object — write to us and we will stop for your account.
Checking for danger. While you talk with the tutor, in a course or with Laura or Daan, the app checks what you say for signs that you may be in danger, for example that you might harm yourself, so it can show you a helpline for your country straight away. The check keeps nothing of what you said. When it finds such a sign, no text of that conversation is kept; our record of the session notes only that such a sign was found, and that record is deleted after 30 days. We run the check on our legitimate interest in keeping the app safe to talk to (Article 6(1)(f)), and we respond to protect your vital interests (Article 6(1)(d) and, where what you said concerns your health, Article 9(2)(c)).
Keeping a record of what you agreed to rests on our legal obligation to be able to show it (Articles 6(1)(c) and 7(1)).
How the app evaluates your learning
We do not use your data for advertising. The app does evaluate your learning automatically, because that is how it teaches: it schedules your reviews from how you answered, the AI scores your sentences and your pronunciation, the app estimates your level, and it writes the report of a chat with Laura or Daan. These evaluations only decide what the app shows you next — which word, which exercise, which correction. They are used for nothing else, and they never lead to a decision with legal or similarly significant effects for you (Article 22 GDPR). A score can be wrong: if you think one is, write to us and a person will look at it.
Who else processes it
We use a small number of specialist providers. Everything that carries your learning — your account, your words, your voice, your photos and your conversations — is processed inside the European Union. Each provider is bound by a data processing agreement.
| Provider | What it does | Where |
|---|---|---|
| Supabase | Hosts the database and your account | Frankfurt, Germany |
| Google Cloud — Vertex AI, running Google’s Gemini models | Judges your spoken sentences, builds a card for a new word, reads the Dutch words out of a photograph, and is the voice tutor’s brain. We have switched off Google’s 24-hour caching of our requests | Frankfurt, Germany (europe-west3); some newer models run in Google’s EU multi-region, which stays inside the EU |
| Google Cloud — Text-to-Speech | Speaks the tutor’s replies, and reads Dutch aloud when you tap ▶ on a word you added or on a sentence in a chat with Laura or Daan, its report or a correction on Today — which can be a corrected version of your own sentence. Those sentences are spoken and sent straight back to your phone; we do not keep them or their audio on our servers (your phone keeps the audio, so it plays again offline) | EU endpoint |
| Google Cloud — Cloud Run and Cloud Logging | Runs the voice tutor’s server and keeps its logs for 14 days | Frankfurt, Germany |
| Deepgram | Converts your recorded speech to text | European Union endpoint |
| Microsoft Azure AI Speech | Scores your pronunciation from a recording, and in Pronunciation practice writes down which word it heard, so the app can tell you when a sound came out as another word | Ireland (North Europe) |
| Lettermint | Delivers the emails our sign-in system sends you — the code to confirm your email address, reset your password or change your email. It receives your email address and that email | The Netherlands (servers in the Netherlands, backups in Germany) |
Outside the European Union
Two services reach outside the EU, and neither carries your learning data:
- Expo (650 Industries, Inc., United States) delivers updates to the app’s code. Each time the app starts, it asks Expo whether a newer version is available. That request carries your phone’s operating system, the app’s version and release channel, the version of the code it runs, a random number created when the app was installed, and, as with any request on the internet, your IP address. It carries no account, email or learning data. Expo is certified under the EU–U.S. Data Privacy Framework.
- Firebase Hosting (Google) serves this website and a small file the app reads when it starts, to check whether an update is required. Google serves both from a data centre near you, anywhere in the world, so it sees your IP address. The website sets no cookies and runs no analytics.
Several of our providers are companies based in, or owned from, the United States — Supabase, Google, Microsoft and Deepgram — even where they process your data in the EU for us. Their data processing agreements include the EU’s standard contractual clauses, and those certified under the EU–U.S. Data Privacy Framework are bound by it as well. Traffic to any of them can pass through the provider’s network near you before it reaches the EU.
For readers in Switzerland: the countries your data can go to are Germany, Ireland and the Netherlands; any EU member state (Google’s EU multi-region and Deepgram’s EU endpoint); and the United States (Expo’s update check). The website is served worldwide.
If you sign in with Apple or Google, or buy a subscription through the App Store, Apple or Google handle that under their own privacy policies. We receive only your email address (or Apple’s private relay address), your name if it is shared, and whether your subscription is active.
We do not sell your data, we do not share it with advertisers, and it is not used to train anyone's AI models.
How long we keep it
Your account, your words and your whole learning history stay until you decide otherwise — and then they go completely, in one step, the same day. There is no archive we quietly keep hold of.
Three things are on a timer: the text of tutor conversations and the server logs are deleted after 14 days, and usage counts after 30 days. Deleting your account removes the conversations and counts at once; copies in the server logs age out within those 14 days.
Your time with the tutor is kept as minutes per day, for as long as your account exists, because it is what your plan is counted against and what your usage page and activity calendar show. It holds no words, only minutes, and it is deleted with your account.
The report of a chat with Laura or Daan is kept until you delete it — open the chat (Practice → Met Laura or Met Daan), tap Details and choose Wis dit gesprek · delete this chat at the bottom — or delete your account. It is a short summary, not the conversation: a few of your sentences with their corrections, so the app can show you the chat again and bring back what you have not mastered yet. Those sentences are erased after 90 days; the date, topic, length and scores stay. The full conversation is deleted after 14 days, like every tutor conversation. The text of a chat with Laura or Daan is also kept on your phone (not on our servers) for 30 days so you can look back at it, and you can delete it there at any time.
Your list of words to practise saying holds only words, their scores, where you said them, your stars per sound and the days you practised — no recording and no sentence. A word leaves the list once you say it well on two different days, and you can take one off yourself by holding it in the list. It is all deleted with your account.
Spoken sentences are kept for as long as your account exists. They are your own record of how you learned each word, and the app shows them back to you on the word, so deleting them on a timer would quietly remove something you may want to look at years later.
Voice recordings and photographs are never written to storage. They exist only for the seconds it takes to process them.
Cookies and storage on your phone
This website sets no cookies, runs no analytics and loads nothing from other websites, so there is nothing to accept.
The app contains no advertising or tracking software. It keeps a few things on your phone because it cannot work without them: your sign-in (in the phone’s secure storage), your settings, audio it has already played so it can play it again offline, the text of your chats with Laura or Daan for 30 days, and your progress in some practice screens. These are strictly necessary for the service you asked for, so the law does not require a separate consent for them. Deleting the app removes them; deleting your account removes what is on our servers.
Your rights
Under the GDPR you may ask us to:
- Access the personal data we hold about you
- Correct anything that is wrong
- Delete your account and everything in it — see Deleting your data
- Export your data in a portable format
- Object to or restrict processing
- Withdraw a consent you gave, such as to scanning, at any time, in the app or by writing to us; it does not affect what was done before
Write to info@sentinz.com and we will respond within one month. We have not appointed a data protection officer, because the law does not require one for the kind and scale of processing we do; that address reaches the people who are responsible.
If you are unhappy with how we handle it, you can complain to the data protection authority where you live or work, or to the Dutch authority, the Autoriteit Persoonsgegevens.
In Switzerland, the Federal Act on Data Protection (FADP) gives you the same rights: to know what we hold about you, to have it corrected or deleted, to receive it in a portable format, and to object. You can complain to the Federal Data Protection and Information Commissioner (FDPIC).
In Ukraine, the Law of Ukraine “On Personal Data Protection” gives you the right to know which of your data we hold, where and why, to see it, to have it corrected or deleted, to object to its processing and to withdraw a consent. You can complain to the Ukrainian Parliament Commissioner for Human Rights.
Deleting your account
You can delete your account from inside the app at any time: Settings → Delete account. It is immediate and it is complete — your cards, review history, spoken sentences, tutor conversations, chat reports, tutor minutes, feedback, the record of what you agreed to and your login are all removed, and nothing can be restored. The only trace left is in server logs, which are deleted within 14 days.
You can also request deletion without installing the app. See Deleting your data.
Age
Sentinz is for people aged 16 and older. Before you start, the app asks you to confirm your age and keeps that confirmation with its date. If you tell the app you are younger, it offers to delete your account at once, and nothing of yours stays with us. If you believe a child has an account, contact us and we will remove it.
Security
Data is encrypted in transit and at rest. Access to your records is enforced at the database level, so one account cannot read another's. Only the minimum number of people can reach production systems, and they sign in with two-step verification. If a breach ever puts your data at risk, we will tell you and the Dutch data protection authority as the law requires.
Changes
If we change this policy we will update the date at the top, and we will tell you in the app before any change that materially affects you takes effect.