Version 1.0 — 4 August 2026. Any change is notified to subscribed customers at least 30 days before it takes effect. This English text is a translation provided for convenience: in the event of any discrepancy, the French version alone is binding.
These terms of sale govern the sale of subscriptions to the Katoptron service, available online, between:
Cyril GOHEL, sole trader (micro-entrepreneur) SIREN 105305783 · SIRET 10530578300018 · APE code 5829C Registered address: 2 rue de l'Orée, 14930 Éterville, France · Contact: gohelcyril@gmail.com
and any natural person acting outside their trade or profession who makes a purchase on the service, hereafter “the Customer”.
VAT not applicable, article 293 B of the French General Tax Code. (As of 1 September 2026, this wording becomes: “VAT not applicable, art. L. 223 et seq. of the CIBS”. The former wording remains acceptable until 31 December 2027.)
Katoptron is an educational simulator of executive efficiency. From data declared by the Customer about their state on the day, it computes activation indicators per brain region, cognitive metrics, a global index and associated protocols.
Katoptron is not a medical device. It makes no diagnosis, offers no treatment and in no case replaces the advice of a healthcare professional. The results are indicative and educational. The Customer acknowledges having been informed of this before any purchase.
| Plan | Price | Type |
|---|---|---|
| Discovery | Free | No account, limited to the current day |
| Monthly | €11 per month | Subscription renewing monthly |
| Annual | €69 per year | Subscription renewing annually |
Prices are stated in euros, inclusive of all taxes for consumers. As the seller benefits from the French VAT exemption scheme, no VAT is charged.
A 7-day free trial is offered once per account, before any paid commitment. No payment method is required to use it.
The seller reserves the right to change its prices at any time. The applicable price is the one in force on the day of the order. Any price change affecting an ongoing subscription is notified to the Customer at least 30 days before it takes effect; the Customer may then cancel free of charge.
Payment is made online by card, through the provider Stripe Payments Europe Ltd. The seller has no access at any time to the card details of the Customer, which are handled directly by Stripe.
The order is confirmed by a summary email. An invoice is made available in the customer area.
Subscriptions are renewed automatically at term, for an identical period, unless cancelled by the Customer.
The Customer may cancel at any time, in a few clicks, from their customer area, with no justification to provide and no email to send. Cancellation takes effect at the end of the period already paid for : the Customer keeps access until that date, with no further renewal.
Pursuant to articles L215-1 and L215-4 of the French Consumer Code, the seller informs the Customer in writing, no earlier than three months and no later than one month before the annual renewal date, of their option not to renew. Failing such information within that period, the Customer may terminate the contract free of charge at any time from the renewal date, and obtain a refund of amounts paid after that date.
Pursuant to article L221-18 of the French Consumer Code, the Customer has a period of fourteen days from the conclusion of the contract to exercise their right of withdrawal, without having to give reasons or bear any cost.
Immediate performance and waiver (article L221-28, 13° of the French Consumer Code). As the service is digital content supplied immediately and without a tangible medium, the Customer is invited, at the time of the order, to:
This double consent is collected through a separate, non-pre-ticked checkbox, and retained as evidence. If the Customer does not tick that box, access is opened only at the end of the fourteen days, and their right of withdrawal remains intact.
More favourable commercial guarantee. Independently of the statutory right above, the seller undertakes to refund in full any request made within 30 days of purchase, on request and without justification. This undertaking is a contractual advantage; it neither reduces nor replaces the Customer's statutory rights.
To exercise either of these rights, the Customer writes to gohelcyril@gmail.com. The refund is made within fourteen days, using the same payment method as the one used for the purchase.
Access to the service is revoked automatically and immediately in the following two cases:
A partial refund, granted as a goodwill gesture, does not revoke access.
This revocation is the direct counterpart of the refund: the Customer cannot keep both the service and its price. The Customer is informed of this before purchase by the present clause.
The health data declared by the Customer never leaves their device. All computation is performed locally, in the browser. No network request carries these declarations. This can be verified by the Customer themselves, by observing their browser's network traffic.
The only data transmitted to the seller is that strictly necessary to manage the account and the subscription : email address, account identifier, subscription status and billing history. It is hosted in the European Union (Ireland).
| Purpose | Legal basis | Retention |
|---|---|---|
| Managing the account and access | Performance of the contract | Lifetime of the account |
| Billing and accounting | Legal obligation | 10 years |
| Preventing free-trial fraud | Legitimate interest | Anonymised, irreversible fingerprint |
Pursuant to the GDPR and the French Data Protection Act, the Customer has the right of access, rectification, erasure, portability, restriction and objection. These may be exercised at gohelcyril@gmail.com, or by deleting their account and all of their data themselves from the customer area (effective, irreversible deletion).
The Customer may export their entire history at any time in CSV and JSON.
In case of difficulty, the Customer may lodge a complaint with the French data protection authority, the CNIL (www.cnil.fr).
The seller undertakes to use reasonable means to ensure the availability of the service, without guaranteeing uninterrupted availability. Interruptions may occur for maintenance, updates or external causes.
If the service is permanently discontinued, the seller undertakes to inform subscribed Customers at least three months in advance, to keep data export available throughout that period, and to refund on a pro rata basis the unused portion of the subscription.
The seller cannot be held liable for decisions taken by the Customer on the basis of the indications provided by the service, which is expressly educational and not medical.
Step 1 — direct complaint. The Customer sends their written complaint to gohelcyril@gmail.com. The seller undertakes to acknowledge receipt within 48 working hours and to reply within 14 days.
Step 2 — mediation. Pursuant to article L612-1 of the French Consumer Code, after a prior written approach to the seller that has gone without a satisfactory reply within two months, the Customer may refer the matter free of charge to the following consumer mediator:
CM2C — Centre de la Médiation de la Consommation de Conciliateurs de Justice
14 rue Saint Jean, 75017 Paris
www.cm2c.net
Mediation is free for the Customer and concludes within 90 days. Recourse to mediation does not prevent the Customer from bringing the matter before the competent courts.
Consumers residing in another European Union member state. The European online dispute resolution platform was permanently closed on 20 July 2025. Cross-border disputes are now handled by the network of European Consumer Centres (europe-consommateurs.eu) or by the competent national mediator.
These terms are governed by French law. In the event of a dispute, and failing an amicable resolution, the French courts have jurisdiction. A consumer Customer may bring proceedings either before the court of their place of residence or before that of the seller's registered address.
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Version 1.0 — 4 August 2026. Any change to these terms is notified to subscribed Customers at least 30 days before it takes effect. In the event of any discrepancy between this translation and the French version, the French version alone is binding.
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