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. | 30 days, then deleted automatically |
| 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 |
| 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. | Until you delete the chat or your account |
| Usage counts and server logs — how many requests your account made today; technical logs of the voice tutor, which include the conversation text | To stop abuse of the paid AI features, keep the service running and diagnose faults. | 30 days |
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. 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. That sentence can contain details from the letter; deleting the card deletes it.
Conversations with the voice tutor are kept for 30 days. What you say to the tutor is stored as text, together with the tutor's replies, so that when a lesson goes wrong we can see why. It is deleted automatically after 30 days, and at once if you delete your account.
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). We do not rely on consent for the core features, because they cannot work without the data. Counting your time with the tutor is part of that contract: 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.
Keeping tutor conversations for 30 days, counting requests and keeping server logs rest on our legitimate interest (Article 6(1)(f)) in keeping the service secure, working and improving. They are kept no longer than 30 days and 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.
We do not use your data for advertising, and we do not profile you.
Who else processes it
We use a small number of specialist providers. All of them process your data inside the European Union. Each 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 | 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 | EU endpoint |
| Google Cloud — Cloud Run and Cloud Logging | Runs the voice tutor’s server and keeps its logs for 30 days | Frankfurt, Germany |
| Deepgram | Converts your recorded speech to text | European Union endpoint |
| Microsoft Azure AI Speech | Scores your pronunciation from a recording, when you ask for it | Ireland (North Europe) |
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: tutor conversations, usage counts and server logs are deleted after 30 days. Deleting your account removes the conversations and counts at once; copies in the server logs age out within those 30 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. The full conversation is still deleted after 30 days, like every tutor conversation.
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.
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
Write to info@sentinz.com and we will respond within one month.
If you are unhappy with how we handle it, you can complain to the Dutch data protection authority, the Autoriteit Persoonsgegevens.
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 and login are all removed, and nothing can be restored. The only trace left is in server logs, which are deleted within 30 days.
You can also request deletion without installing the app. See Deleting your data.
Children
Sentinz is not directed at children and we do not knowingly collect data from anyone under 16. If you believe a child has created 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.