Privacy policy
Last updated: 5 November 2026
This English version is provided for your convenience. The French version is the one that binds.
This policy explains how your personal data is processed when you use Voyelle, its website and its app. The data controller is OpaleCrest, the trade name of Mathieu Corne, a sole trader (SIREN 943 061 820), 50 avenue des Champs-Élysées, 75008 Paris, France. For any question about your data, write to privacy@opalecrest.com.
In short
Voyelle keeps what it needs to schedule your reviews and show you your progress. None of your personal data is sold or used for advertising, and Voyelle shows no ads. A teacher sees who joined their class; as for your progress, they and any institution only ever see aggregated data, never yours in particular. A student society only sees aggregated figures about its groups, never a name. If you choose to, your reviews can also support scientific research, as aggregated and anonymous statistics.
Data we process
Account and identity (Opale ID) — Your Voyelle account is opened with Opale ID, a service we publish ourselves, under the same entity as Voyelle, which holds the identity and consents for all our products. Voyelle receives from it an identifier specific to Voyelle, which cannot be used to find you in our other products, and whether your recovery address has been verified. Voyelle keeps that identifier, the display name you choose, your language, your time zone and whether you want the mascot to move. When you change a way of signing in at Opale ID (password, passkey), Voyelle receives a notice of it, which it shows you the next time you sign in.
Your decks — The decks you add to your study set, with their dates. Members do not write, import or publish cards: decks come from the Voyelle library and from teachers. If you are a teacher (a professor or an institution administrator): the private decks you hand to your classes and the official decks of your institution that you write, their cards, topics, translations and dates. These cards are text only: Voyelle keeps no image or sound from its members, and no file is imported; the library's images and sounds come from Voyelle. A deck a member wrote before writing was kept for teachers is still kept, readable by those who have it, and can no longer be edited.
Your reviews and progress — For each card reviewed: your answer, how long you took, the date, the kind of session (daily review, a targeted session on a deck or a topic, a first session, an intensive revision, studying ahead) and the resulting state used to schedule the next review; answers given in an intensive revision are kept apart and do not change that schedule. From these reviews we work out your mastery of each topic, an estimate of your level in each subject and a readiness score for each certification, as well as your streak, your streak freezes, experience, level, badges, finished paths and weekly league. When you tell us you passed an exam, we keep its date. With Voyelle Plus, we also keep the order you give new cards (priority decks and topics).
Your targeted sessions and the free plan's limits — To apply the free plan's limit on targeted sessions: each day, the decks and topics you asked for a targeted session and whether it was granted. When a limit of the free plan stops you (one more targeted session, an intensive revision, studying ahead, the order of new cards): the day, the limit concerned and how many times.
What you open to learn — At most once a day for each: opening “Understand” on a card, opening an Explorer and the object it opens on, and opening a path. These markers, like the kind of your sessions, feed the product's aggregated statistics; they are given to no one and are erased with your reviews.
Your deck requests — When you ask for a missing deck, from the library, a search or your assistant, or back another member's request (“Me too”): the subject and, where relevant, the syllabus as you write them, where the request came from, its date and whether you have seen it published. Requests on the same subject are grouped into one shared request, which keeps the subject, its language, the domain and its status (received, planned, published, declined) without naming anyone; your support is linked to your account. Other members see the subject of an open request and how many back it, never who asked: do not write personal data in it.
Searches with no result — When a library search finds no deck, we count the search (normalised, from three characters), its language and the day, without your account or anything that could identify you.
Your contributions — Your reports and their reason, and, if you request a role, your message and, where relevant, the attestation of an administrator of your institution.
Names others see — Your display name, a live session nickname, and the title of a class or a shared deck are checked automatically before they are shown (insults and, for a name or a nickname, contact details and reserved names); a refused name is not stored. When you report another member's name: your account, the name reported, the reason and your details. The member whose name is reported still sees their own, but others read “Member” followed by four digits until we keep or erase that name. The host of a live session can likewise hide a nickname for the rest of the session.
Live sessions — For a live session: its host, the deck shown, and for each participant the nickname chosen, their answers, how long they took, their score and, where relevant, the fact that their nickname was hidden. A participant can join a session without an account, with a nickname only. Questions and the leaderboard are relayed to participants in real time from our servers in France, without being stored there.
Apéro games — For an Apéro game, which every player joins with their account: its host, the decks chosen, and for each player their nickname, their moves in each round (answers, votes, forfeits suggested), their points, their feats, the titles they receive or vote for, and the title they show with Voyelle Plus. Cards missed during the game come back into your reviews. The real-time relay only sends players a change signal, with no content: each player then reads their own view from the service.
The daily challenge — Your attempt at the daily challenge: your answers, how long they took and your score. Your rank for the day is worked out among finished attempts, without showing your name.
Subscription and payment — On the web, payment is handled by Stripe: we never receive or store your card number, and we keep the Stripe identifiers of your subscription, its period, status and dates. In the Android app, payment goes through Google Play: we receive and keep the purchase token, the order identifier, the period, status and dates of the subscription, which we verify with Google; the purchase carries an identifier of your Voyelle account, so we can check it is yours. If, before paying on the web, you ask for immediate access to Voyelle Plus, we keep with the subscription the date and time of that request and the version of the terms of sale in force. If you give a year of Voyelle Plus on the web: the gift code, the email address and identifiers of the Stripe payment, the amount, the immediate access request and the version of the terms of sale, the dates of payment and redemption, and the account that redeemed the code. Voyelle does not write to the person you give it to: you pass the code on yourself. If you withdraw without signing in, we keep the email address you give, the date of the request and the amount refunded.
Notifications — To remind you to study, we keep the notification address your browser or Android phone gives us if you turn notifications on. On Android it goes through Google Firebase Cloud Messaging; in a browser, through the browser maker's notification service.
Your feedback — When you write to us from the app to report a problem or suggest an idea: your message, its type, the address you give for a reply if you give one, your plan and technical details about the app and the device. The message is also sent to us by email.
Your institution — If you tell us, the institution where you study and, where relevant, your course or certification, along with your university email once verified with a code. This information is only used for aggregates: for example, the number of students from an institution who study with Voyelle, shown to a teacher from five students upwards, never their names.
Your classes and invitations — The classes you created or joined, with the date you joined; the invitation links you shared, their kind and how many times they were used; the free month of Voyelle Plus when a teacher you invited is granted their role.
Your study groups — The group you created or joined, its members, the date you joined, the decks shared in it and who shared them; the streak freeze given when a member you invited reaches a seven-day streak.
A student society — If you request a society's space or join its committee: the society (its name, faculty or campus, institution, programmes, official link, RNA number if given, logo and the request's message), the society that recommended it if any, its committee members with the date they joined, and the result of checking its RNA number (the society's official name, city and state in the public directory). If you join a society's year group: your membership of that group, as for a class, and the link you arrived through.
University emails given by a teacher — When a teacher gives us their students' university emails: each address, the class, the date the invitation and any reminder were sent, and its status (invited, joined, unsubscribed). The person invited learns about it from the invitation itself, which names the teacher and links to this policy.
The signatory of an agreement — When a teacher suggests a partnership: the email address of the signatory they name. If the signatory accepts the agreement online: their name, job title, statement of authority, the date and time of acceptance, the IP address and browser used, the version accepted and the copy produced.
A partnership request — When you fill in the form for institutions: the institution and faculty, your name, job title, email address, phone number if you give one, your interests, the subjects, the rough number of students and your message.
Your journey — When you arrive on the website, your browser draws a random journey identifier, kept for the length of your visit in its session storage, together with the campaign you came from if any. It travels with your links to the app, so that later steps join the same journey. Each step is recorded with that identifier: the page the journey started on, a trial card played on the home page, Karti's demo in the web app before the account exists (started, finished or skipped, and whether the card played was right), then, by Voyelle, account creation, the first session, opening the checkout and the subscription. These steps contain neither your name, nor your email, nor your IP address, and are matched with the pages read during the same visit.
The ad that brought you here — If you arrive from a Google ad, the page address carries an identifier for that click, assigned by Google. It is only passed on to the app and kept if you agree, in the message shown when you arrive, that Voyelle may tell Google Ads that your sign-up and your subscription came from that ad. See the “Google Ads” section.
Your choice to support research — If you agree to support scientific research, in Voyelle's settings or in your Opale ID space, Opale ID keeps that choice and each change to it, with its date, where you made it and the version of this policy in force at the time; Voyelle keeps the date it offered you the choice. This choice collects no new data: it only decides whether your reviews may be part of the statistics given to research labs.
Your assistant, if you connect it — You can use Voyelle from your own AI assistant, such as Claude by Anthropic or ChatGPT by OpenAI, through the connector. The assistant reads what you have to study (your decks, your progress, your session plan), searches for and adds a library deck, sends a deck request and gives you the links to study in Voyelle. It does not quiz you in the conversation, and it writes and translates no card. What it reads in Voyelle is then sent to its provider at your request and under that provider's terms, under your account with them. Otherwise, Voyelle sends them nothing.
The demo before the account — Before you create your account, the web app may have you play a short demo with Karti. Voyelle keeps nothing of it while no account exists: the card you play, your answer and its time stay in your browser, for thirty days at most. If you create your account, that card is sent to Voyelle, its deck joins your study set and your answer becomes your first review. The demo's steps join your journey (see “Your journey”).
Purposes and legal bases
| Processing | Purpose | Legal basis |
|---|---|---|
| Account and access (Opale ID) | Authenticating you and giving you access to the service | Performance of the contract (art. 6.1.b) |
| Decks and reviews | Keeping your decks and, for a teacher, the decks they write, scheduling your reviews, applying your plan's limits, measuring your progress and showing it to you | Performance of the contract (art. 6.1.b) |
| Deck requests and searches with no result | Grouping requests, choosing which decks to write from demand and telling you when yours is published | Performance of the contract (art. 6.1.b) for your requests; legitimate interest (art. 6.1.f) for counting searches with no result, which does not concern you personally |
| Apéro and the daily challenge | Running a game, its rounds and titles, and the daily challenge with its ranking | Performance of the contract (art. 6.1.b) |
| Leagues and rankings | Placing you each week in a league of members at a comparable level | Performance of the contract (art. 6.1.b) |
| Quality of shared decks | Measuring the difficulty and quality of the library's cards and official decks, spotting cards to fix | Legitimate interest (art. 6.1.f) — ours and members' in accurate decks |
| Visible names and name reports | Keeping out names that insult, mislead or give contact details, handling name reports | Legitimate interest (art. 6.1.f) — members' interest in not being shown an insulting or misleading name |
| Contributions and reports | Handling reports and role requests | Performance of the contract (art. 6.1.b); for removing unlawful content, legal obligation (art. 6.1.c) |
| Live sessions | Running a session and showing scores | Performance of the contract or the terms of use (art. 6.1.b) |
| Class dashboard and partner institutions | Showing a teacher or an institution the aggregated mastery of the learners of its decks | Legitimate interest (art. 6.1.f) — the teacher's in adapting their course; aggregates only |
| Product statistics | Improving Voyelle (review scheduling, cards, paths, Explorers, plans) from aggregated and anonymised statistics on how all members learn: kinds of sessions, response times, openings of “Understand”, Explorers and paths, free plan limits reached | Legitimate interest (art. 6.1.f) — ours in improving the service; these statistics are given to no one |
| Scientific research with labs | Giving research labs that study memory and learning aggregated and anonymised statistics, drawn only from the reviews of members who agreed | Consent (art. 6.1.a), optional and unticked by default, given in Voyelle's settings or in your Opale ID space and withdrawable at any time, with no effect on the service |
| Subscription, payment and withdrawal | Collecting the subscription or a year of Voyelle Plus given, verifying Google Play purchases, redeeming a gift code, handling a withdrawal and its refund | Performance of the contract (art. 6.1.b); keeping accounting records: legal obligation (art. 6.1.c) |
| Classes and invitations | Running classes, invitation links and the free month | Performance of the contract (art. 6.1.b) |
| Study groups | Running groups, deck sharing and the streak freeze given | Performance of the contract (art. 6.1.b) |
| Student societies | Running a society's space, its committee, its year groups and its links, showing it aggregated statistics, presenting it on its programmes' pages | Performance of the contract (art. 6.1.b) |
| Verifying a society | Checking a society's RNA number in the public directory of associations before giving it the “Verified society” badge | Legitimate interest (art. 6.1.f) — that of members and teachers to know a society really exists |
| Class invitations by university email | Inviting the students a teacher names to join their class, on the teacher's behalf | Legitimate interest (art. 6.1.f) — the teacher's in bringing their class together; every invitation lets you object in one click |
| Partnership agreement | Sending the agreement to the named signatory, collecting their acceptance and keeping proof of it | Legitimate interest (art. 6.1.f) for sending it; performance of the agreement and proof of acceptance for the record |
| Partnership requests | Answering an institution that writes to us and preparing the agreement | Legitimate interest (art. 6.1.f) — ours and the institution's in exploring a partnership |
| Notifications | Reminding you to study and about your streak | Consent (art. 6.1.a), given by turning notifications on and withdrawable at any time |
| Your feedback | Handling a problem or an idea, and answering you if you wish | Legitimate interest (art. 6.1.f) |
| Journey measurement | Understanding how visitors move from the website and the demo to the app and to subscribing, and where they stop | Legitimate interest (art. 6.1.f) — ours in knowing whether the journey is clear |
| Google Ads measurement | Telling Google Ads that a sign-up or a subscription came from one of its ads, to know what each campaign brings in | Consent (art. 6.1.a), given in the message shown on arrival and withdrawable at any time |
| Website traffic measurement | Knowing which pages are read, and which website or campaign people come from | Legitimate interest (art. 6.1.f) |
| Security of the service | Preventing abuse and attempts at unauthorised access, telling you about a change to your ways of signing in | Legitimate interest (art. 6.1.f) |
Personalised scheduling
Your review schedule, mastery by topic, readiness score and league are worked out automatically from your answers. The automatic check of a name only refuses it before it is shown; you can choose another. These calculations have no legal effect on you and do not significantly affect you within the meaning of article 22 of the GDPR.
Teachers and partner institutions
When you join a teacher's class, they see your display name in their class list and, if they invited you by university email, the status of that invitation. As for your progress, the teacher and the institution only receive aggregated data, such as the average mastery of each topic. No individual progress data, and none of your answers, is shared with them without your express consent. Research work, including with a partner institution, follows the section Supporting scientific research.
Student societies
A student society (a students' union, a peer tutoring group) can open year groups on Voyelle and share them with its members. If you join one of these groups, the society is named there, with its logo, and you can leave it at any time from your classes. The society never sees your name or your progress: it only receives aggregated figures across all its groups (members, arrivals through its links, active members per week, cards reviewed, decks studied, average mastery by topic, teachers invited and joined, societies invited). A figure about fewer than three people stays hidden.
Committee members of a society see the other committee members' display names. The society's name, campus, official link, approved logo and badge are public on the pages of the programmes it follows. When a society gives its RNA number, Voyelle checks it in the French State's public directory of companies and associations: only that number is sent there, and Voyelle keeps the society's official name, city and state as read there. A dissolved society loses its badge.
Supporting scientific research
Voyelle may give research labs that study memory and learning statistics about how people review, through a Research offer made to labs, per project and per year, and never to a company. These statistics are aggregated and anonymised: they describe groups of members, for example the share of cards remembered thirty days later depending on the interval between two reviews. Labs never receive your answers one by one, nor your name, your email, your identifier or anything else that could lead back to you.
Only members who agreed contribute. This choice is optional and unticked by default: it is offered in Voyelle's settings and, once only, on the home page after your first week. You can withdraw it at any time, as easily as you gave it, in Voyelle's settings or in your Opale ID space, and nothing changes in the service. After a withdrawal, your reviews are left out of the statistics produced from then on; those already given, being anonymous, can no longer be linked to you, so they cannot be taken out of them. Deleting your Voyelle data also withdraws this choice.
These statistics are separate from those used to improve Voyelle: aggregated and anonymised as well, the latter cover all members, rest on our legitimate interest and are given to no one. You can object to them by writing to privacy@opalecrest.com.
Recipients
Your data is only shared with the providers needed to run the service. Opale ID is not one of them: we publish it ourselves, under the same entity. The providers are:
- OVH SAS (2 rue Kellermann, 59100 Roubaix, France) — servers located in France that host the website, the app and the service's database, run its requests, send its emails (including class invitations and the message sent to the signatory of an agreement) and relay live sessions and Apéro in real time, storing nothing of them;
- Stripe Payments Europe, Ltd. (Ireland) — payment and management of subscriptions taken out on the web;
- Google Ireland Limited (Ireland) — Google Play, for subscriptions taken out in the Android app, and Firebase Cloud Messaging, for Android notifications;
- Google Ireland Limited (Ireland) — Google Ads, only if you agree, for the measurement described below;
- our email service, which receives the messages sent to our addresses;
- browser notification services (Apple, Google, Mozilla, Microsoft), which deliver a notification.
Other members see what you choose to make visible: your display name and weekly experience in your league, your display name in your study groups and in the classes you join, your display name on a society's committee for the other committee members, your nickname in a live session, your nickname, points, suggested forfeits and titles in an Apéro game, the decks you share in a group and, if you are a teacher, the decks you hand to your classes or write for your institution. The subject of a deck request is visible to other members, never the name of whoever asked. If you use Voyelle from your assistant, its provider (Anthropic for Claude, OpenAI for ChatGPT) receives, at your request, what the assistant reads in Voyelle and the answers you give it. Research labs receive no personal data (see Supporting scientific research).
Transfers outside the European Union
The website, the app, the service's database and its email sending are hosted in France. Google and Stripe may transfer data to their parent companies in the United States. These transfers are covered by the EU–US adequacy decision (Data Privacy Framework), under which these providers are certified, and, should it be invalidated or suspended, by the standard contractual clauses adopted by the European Commission (decision 2021/914). If you connect your assistant, what its provider receives, it receives under your account with it and under its own terms.
How long we keep data
| Data | Retention |
|---|---|
| Account, private decks, reviews, progress, targeted sessions, limits reached, openings of “Understand”, Explorers and paths, daily challenges | As long as your account exists, then erased when it is closed; an account left unused for three years is erased, after a warning one month before |
| Apéro games | Your participation, moves, feats and titles: as long as your account exists; the game itself, with how its rounds went: as long as its host's account exists |
| Official or Voyelle-validated cards written by a teacher, and shared decks other members study | As long as the deck exists; when their author closes their account, they stay without being linked to their identity |
| Your support for a deck request | Until you withdraw it or your account is closed; a shared request no one backs any more is erased, unless Voyelle planned or published it, in which case it stays without naming anyone |
| Searches with no result (a count with no link to any member) | Thirteen months, then erased |
| Technical request logs (IP address, requested address, time, response) | 365 days, then erased |
| Nicknames, answers and scores in a live session | Ninety days after the session ends, then erased |
| Reports and removal decisions | One year after the decision, so we can account for it |
| Role requests | The request, its message and the decision are kept as long as the account exists |
| Name reports | One year after the decision, then erased; when the reporter closes their account, the report is no longer linked to them |
| Classes, groups and invitations | As long as the class, the group or your account exists; you can leave a class or a group at any time |
| A student society, its logo and the check of its RNA number | As long as the society has a space on Voyelle; your committee seat, as long as you hold it or your account exists |
| Days of Voyelle Plus given | As long as your account exists |
| University email given by a teacher | Sixty days after the invitation if the student never joins, then erased; after an unsubscribe, only a fingerprint of the address is kept, so we never write to it again |
| Email address of the named signatory | Six months without acceptance, then erased |
| Acceptance of an agreement and its copy | The term of the agreement, then five years (general limitation period) |
| Partnership request, sent through the institutions form or by a teacher, that did not lead to an agreement | Three years after it was sent, then erased |
| Notification addresses | Until you turn notifications off, or the notification service reports the address as expired |
| Your feedback | Erased with your account, and at the latest two years after it was sent |
| Notice of a change to a way of signing in | One year after it is received, then erased |
| Website visits | Anonymous from the moment they are recorded |
| Link between your journey and your account | Ninety days after the account is created, then erased |
| Journey steps (a random identifier and the arrival campaign, never your identity) | Without time limit, as anonymous statistics: after ninety days nothing can link them to you |
| Google ad click identifier, if you agreed | Ninety days after your consent, the period after which Google no longer matches a subscription to a click; erased sooner if you withdraw your consent |
| Your choice about ad measurement | Six months, in a cookie; after that you are asked again if you come back from an ad |
| Your choice to support research and its changes | At Opale ID, as long as your account exists, to keep proof of your choice; when your Opale ID account is deleted, this history is no longer linked to you and is erased five years after its last change |
| Aggregated and anonymised statistics (product and research) | Without time limit: they contain no personal data |
| Subscription as Voyelle records it | As long as your account exists, then erased |
| Invoices, payment records, immediate access requests, paid gifts and withdrawal requests | Ten years from the end of the financial year concerned (article L. 123-22 of the French Commercial Code), at Stripe and Google Play for invoices and payments |
| Database backups | Encrypted; only the last 30 daily backups are kept, so erased data disappears from them at most 30 days later |
Google Ads
When you arrive from a Google ad, the page address carries an identifier for your click, assigned by Google. A message then asks whether Voyelle may tell Google Ads that your sign-up and your subscription came from that ad. If you decline or do not answer, the identifier stays in your browser for the length of the visit, without being passed on or kept.
If you agree, the identifier travels with your journey to the app and is kept there with the date of your consent. If you create your account, we send Google Ads that identifier, the date of the sign-up and a reference; if you subscribe, that identifier, the date of your first payment, its amount and a reference. Never your name or email, and stating that you did not consent to ad personalisation: the transmission only serves to count the sign-up and the subscription in the campaign's results. You can withdraw your consent at any time by writing to privacy@opalecrest.com: the identifier is then erased and nothing more is sent.
Minors
Voyelle is reserved for people aged 16 or over. Voyelle does not ask for your date of birth. Joining a live session without an account only takes a nickname: nothing else is asked of the participant. If an account was opened by someone under 16, their legal guardian can write to privacy@opalecrest.com to have it deleted.
Your rights
Under the GDPR, you have the right to access, rectify and erase your data, to restrict or object to its processing, and to data portability. You can delete your Voyelle data or your account by following the Delete your data and Delete your account pages, or write to us at privacy@opalecrest.com. We answer within one month (extendable by two months for complex requests, art. 12.3 GDPR); we may ask for proof of identity. You can also lodge a complaint with the CNIL, the French data protection authority (cnil.fr).
Data breach notification
If a breach of your data is likely to put your rights at risk, we notify the CNIL within 72 hours and tell you directly when the regulations require it (art. 33-34 GDPR).
Cookies and traffic measurement
This website uses no third-party analytics service. It sets only one cookie, and only if you arrive from an ad and answer the message that appears: it remembers your choice about ad measurement so we do not ask again, and the app reads it. Your browser's session storage keeps your journey identifier for the length of the visit.
The app only keeps on your device what it needs to work and your preferences, with no analytics or advertising: your sign-in; your preferences (theme and language, in two cookies kept for a year, sound, vibration, mascot animations); display markers, such as a message or the demo already seen; the card played during the demo, for thirty days at most or until you create your account; in the Android app, reviews made offline, until they are sent. If you allow the camera to join a live session by its QR code, the image is read on your device, never sent or kept. On the website, adding ?track=off to the address stops visit and journey measurement in that browser, which remembers it.
Error reports. When an error occurs, the Android app and the service send us a technical report: the kind of error, the screen or route, the version. It contains nothing you typed, none of your identifiers and not your email address.
Website visits. For each page read, we record the page, the website you came from and, where relevant, the campaign. To count visitors without tracking them, we compute a fingerprint of your IP address and your browser, mixed with a secret value that changes every day: it can neither reveal your IP address nor recognise you from one day to the next. Nothing is stored on your device.
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