Terms of use

Last updated: 5 November 2026

This English version is provided for your convenience. The French version is the one that binds.

These terms govern the use of the voyelle.opalecrest.com website and of the Voyelle web and Android apps, published by Mathieu Corne, a sole trader operating under the trade name OpaleCrest (SIREN 943 061 820). They apply to members who hold an account and to participants who join a live session with its code. By using Voyelle, you accept them.

The service

Voyelle is a flashcard app built on spaced repetition. It schedules each card according to your answers, offers a library of ready-made decks written by Voyelle and the decks teachers hand to their classes, lets you ask for a missing deck, track your progress by topic, and run or join live sessions and Apéro games. Cards are written by Voyelle and by teachers, as text only: members do not create, import or publish them. Paid access to some limits is governed by our terms of sale.

Voyelle is a memorisation aid. It replaces neither a course nor a certification's official documentation, and does not guarantee success at an exam. Voyelle is not affiliated with any certification body; certification names belong to their owners.

Account and access

A Voyelle account is opened with an Opale ID account, the identity service we publish for all our products. Studying in Voyelle requires an account; only the trial card on the website's home page and Karti's demo, before the account is created, can be played without one. No answer to the trial card is kept; the card played during the demo stays in your browser and only becomes your first review if you create your account.

Voyelle is reserved for people aged 16 or over. By creating an account, you confirm that you have reached that age. You are responsible for keeping your sign-in details confidential and for what is done with your account.

Roles

Every member studies the library's decks and those their teachers hand them, and can report content and ask for a missing deck. Some members are given a role that extends what they can do: a teacher whose status has been checked writes the private decks they hand to their classes and the official decks of their institution; the administrator of a partner institution vouches for its teachers and writes those decks too. Roles are granted by Voyelle and may be withdrawn if these terms are breached.

Your content

Only teachers (professors and institution administrators) and Voyelle write cards and decks, as text only, with no image, no sound and no file import. A teacher remains the owner of the cards and decks they write. Everyone, teacher or not, is alone responsible for what they write in Voyelle (cards, decks, the subject of a deck request, a forfeit suggested during an Apéro, a name or nickname), and warrants that they hold the necessary rights to each piece of content.

In particular, you may not write into Voyelle:

• a full or substantial copy of a textbook, course, book or any other protected work, without its owner's permission;
• real exam questions, whatever their source, including those a certification body covers with a non-disclosure agreement;
• unlawful, hateful, defamatory, violent or sexual content, or content that invades someone else's privacy;
• other people's personal data without their consent.

You alone are responsible for any infringement of copyright or other rights committed through the content you write, and you indemnify OpaleCrest against any third-party claim on that basis.

To run the service, you grant Mathieu Corne a non-exclusive, free, worldwide licence, for the duration of the rights, to host, reproduce and display your content in Voyelle. For a deck a teacher hands to their classes or shares in a group, this licence also covers its distribution to their members; for an official deck, its distribution to other users and the corrections needed for its accuracy. It continues for official or Voyelle-validated cards and for decks other members study if the teacher closes their account. A private deck is visible only to its author, the members of the classes they hand it to and the groups it is shared in.

Three kinds of cards, three responsibilities

Cards in a teacher's private decks, which they hand to their classes, are written under that teacher's sole responsibility. So is a card a member wrote earlier that was never validated. For these cards, OpaleCrest acts only as a host.

“Made by Voyelle” and “Validated by Voyelle” cards have been reviewed and approved by OpaleCrest, the publisher of Voyelle, for their teaching accuracy: the former are written by Voyelle for its library, the latter written by a teacher or, earlier, by a member. They fall under its responsibility as publisher, as do library decks still awaiting review by a qualified person, which carry no mark until their cards are validated. This validation does not rule out every mistake: an inaccurate card can be reported at any time and is then corrected or removed. It implies no endorsement by, or affiliation with, any exam body.

Official cards are written by the teachers of a partner institution on that institution's decks, and those teachers vouch for their content. They carry an “Official” mark with the institution's name.

Reporting content

Every card has a “Report” button, available to every member, for flagging a copyright infringement, a mistake, inappropriate content or another reason. Anyone, member or not, can also report content to us at contact@opalecrest.com, stating:

• their name and a way to reach them;
• the deck or card concerned, with its address if possible;
• the reason for the report and, for a copyright infringement, the work concerned and the capacity of the person reporting (author, publisher or authorised agent).

We review every report diligently. Manifestly unlawful content, in particular a card that copies a protected work without permission, is removed promptly. The author of removed content is told, with the reason for the decision, and can challenge it by writing to us; we then review the decision again. A user who repeatedly writes unlawful content has their account suspended.

Our role as a host

For content written by teachers and other users, Voyelle acts as a hosting provider within the meaning of article 6 of French law no. 2004-575 of 21 June 2004 on confidence in the digital economy and of Regulation (EU) 2022/2065 on digital services. As such, Voyelle has no duty to monitor the content it stores, and can only be held liable if it fails to act promptly to remove unlawful content once aware of it. “Made by Voyelle” and “Validated by Voyelle” cards, reviewed and approved by OpaleCrest, are on the other hand under its responsibility as publisher.

Live sessions

The host of a live session chooses the deck shown and gives participants the access code. Each participant picks a nickname, visible to other participants and the host, and agrees that it will be neither offensive nor misleading. The host can remove a participant from the session.

Each player in an Apéro game joins it with their account and a nickname, visible to the other players. Forfeits suggested during the game are read by the whole table: they follow the rules of “Your content” and must neither endanger nor humiliate anyone. Everyone remains free not to perform a forfeit.

Asking for a deck

Every member can ask for a missing deck, from the library, a search with no result or their assistant, and back another member's request. Requests on the same subject are grouped; other members see their subject and how many back them, never who made them. A request does not bind Voyelle: we freely choose the decks we write, and tell you when the one you asked for is published.

Names others see

Your display name, a live session nickname and the title of a class or a shared deck are checked before others see them: a name or nickname that is offensive, reserved or gives contact details, and an offensive title, are refused, and you can choose another.

Any member can report another member's display name, giving a reason. From the report on, other members read “Member” followed by four digits instead of that name, in leagues, groups and classes, until we keep or erase it; the member concerned still sees their own, and changing it closes the reports against it. A name we have kept is no longer masked by a new report. The host of a live session can likewise hide a nickname, which then reads “Participant” followed by four digits for the rest of the session.

Classes and invitations

A teacher can create a class for a course and share its code, link or QR code. A student who joins a class receives the teacher's decks and can leave at any time. The teacher sees who joined the class and the class's mastery by topic, as aggregates, never one student's answers or individual progress.

A member can invite their teacher or colleagues with a personal link, which they share themselves or send from their own mailbox. Voyelle writes to no one on a member's behalf, except in the two cases described below, each at the express request of the person who takes responsibility for it.

When a teacher who arrived through a student's link is granted the teacher role, that student receives one month of Voyelle Plus for free, once per teacher and at most three times a year. This free month has no monetary value and cannot be exchanged for anything.

Study groups

A member can invite classmates to their study group through a personal link they share themselves. Members of a group see each other's display names and the decks shared in it, and can share their own. Anyone can leave the group at any time; the group ends if the member who created it leaves.

When a classmate who came through that link, or a friend who came through the link inviting them to Voyelle, reaches a seven-day streak, they and the member who invited them each get a streak freeze, added to their plan's and never expiring; at most three freezes received this way stay in reserve, and the inviting member receives ten a year at most. This freeze has no monetary value and cannot be exchanged for anything.

Inviting a class by university email

A teacher can give Voyelle the university email addresses of the students on their course, so that Voyelle invites them to join the class on the teacher's behalf. Only addresses on a university domain are accepted. The teacher undertakes to give only the addresses of their own students, for the sole teaching purpose of inviting them to the class.

Each invitation names the teacher and the class, and carries a link to join and a link to stop receiving anything. Only one reminder is possible. The addresses of students who never join are erased sixty days after the invitation; the addresses of students who unsubscribe are only kept in a form that prevents us from ever writing to them again.

A student can also add and verify their university email in their settings, and then joins the classes that invited them. They can remove that address at any time.

Institution partnerships

A teacher can suggest that their faculty or department becomes a partner and name, by email, the person authorised to sign. At the teacher's express request, Voyelle sends that person a single message that names the requesting teacher and gives access to the partnership and the agreement.

The signatory can accept the agreement online, giving their name and job title and confirming that they are authorised to commit the institution, or sign it through their own process. An online acceptance is recorded with its date and time and the version accepted, and a copy is sent to the signatory and to OpaleCrest, which countersigns. The partnership is then governed by the agreement.

Progress, leagues and rewards

Experience, levels, badges, streaks and league rankings measure how regularly you study. They have no monetary value, cannot be traded and cannot be exchanged for anything. Your display name and your experience for the week are visible to the members of your league.

Acceptable use

You agree to use Voyelle in good faith and not to disrupt it. In particular, the following are prohibited: automated extraction of decks or cards, unauthorised bots, any attempt at unauthorised access, manipulating rankings, harassing other users and any use that breaks the law.

The decks and cards available with a Voyelle account form a database whose making required a substantial investment: extracting or reusing them, even in part, is prohibited without our consent (article L342-1 of the French Intellectual Property Code). We object to their text and data mining, including to train artificial intelligence models (article L122-5-3 of the same code). The site's public pages remain free to be read, quoted and indexed.

We may suspend a user's access, withdraw a role or remove content in the event of a serious breach of these terms, without prejudice to the rights consumer law grants you. Except in an emergency or where the law requires otherwise, we give our reasons.

Availability and liability

Voyelle is provided as is. We use reasonable means to keep it available and the cards it validates accurate, without guaranteeing uninterrupted access or error-free cards.

Closing your account

You can delete your Voyelle data or your account at any time, as explained on the Delete your account page. Your private decks and your progress are then erased, as described in our privacy policy. A running subscription is cancelled separately, as described in our terms of sale.

An account left unused for three years is erased, with its decks and progress, after a warning one month before; signing in before then keeps it. An account with a running Voyelle Plus subscription is never erased this way.

Changes to these terms

These terms may change. Changes take effect fifteen (15) days after they are published on the website. If you keep using Voyelle after that period, you accept the updated terms; if you do not accept them, you can close your account.

Change of publisher

Voyelle is currently published by Mathieu Corne, a sole trader. Its operation may be transferred to any company that succeeds him, in particular following a change of legal form, without affecting your rights.

Governing law

These terms are governed by French law. In the event of a dispute, you may bring the matter before any court with territorial jurisdiction of your choice, in particular the court of your place of residence.