Terms and conditions

1. Who provides the service

These terms govern the use of https://sellat.app and the purchase of its services, which are provided by Cristian Cascante Portabella, tax ID 38846956W, with address at Plaça d'Ibèria 1, 08014 Barcelona (Spain). Sellat is his trading name. Contact: hola@sellat.app.

The Legal notice, the Privacy policy and the Cookie policy, linked in the footer of every page, supplement these terms.

By creating an account, creating a proof, connecting a shop or purchasing a service, you accept these terms in the version in force at that moment.

2. What Sellat is

Sellat generates a verifiable proof that a specific digital file existed in an exact state at a given moment. To do so, it computes the file's SHA-256 cryptographic fingerprint and anchors it in public records, without needing to keep the original file.

On that basis, optional paid services are offered, described on the pricing page and in section 11.

3. Account and free proofs

You can create free proofs, with or without an account. They are intended for individual use at a moderate volume, and we may limit their rate and their daily number to protect the service, and change those limits at any time.

On the free account, the proofs you create through the API are anchored in groups: they go into a batch that closes at fixed times (UTC) and is anchored after it closes. The API documentation states how often it closes. The proof is just as verifiable; only the time of anchoring changes. The qualified timestamp, if you request it, does not wait for that anchoring: it bears the time it is issued. This does not apply to proofs you create on the website.

Each person may have only one account. Creating accounts or proofs automatically outside the API is not allowed, nor is getting around the service’s limits, for example with several accounts or by changing IP address.

The welcome qualified timestamp is one per person: it is not granted to an email address that has already used it with another account, even if written differently (for example, with an alias), nor to temporary email addresses. If on a given day the maximum number of welcome timestamps is reached, yours is not lost: it stays in your account for another day.

Paid services require an account. You sign in with a link sent to your email address or with a Google or Microsoft account, and the account is created the first time you sign in. You must be of legal age to create an account and to purchase.

You are responsible for safeguarding access to your email and to the account you sign in with: anyone who accesses them can sign in to Sellat in your name.

4. What a proof demonstrates, and what it does not

Sellat attests that a specific cryptographic fingerprint existed on a given date, and makes it possible to check whether any file is or is not exactly the same one that produced it.

Sellat does not attest to the authorship of the file, the ownership of the rights over its content, the truthfulness of what the file states, or the identity of whoever created the proof beyond the account used.

The assessment of a proof is in every case a matter for the competent judge, arbitrator or authority. Sellat does not guarantee the outcome of any claim, proceedings or negotiation.

5. Publication in public records: permanent and irreversible

So that the proof can be verified by third parties without depending on Sellat, your file's fingerprint — or a Merkle root that includes it — is published on public networks (Polygon and, through OpenTimestamps, Bitcoin). That publication is permanent and irreversible: neither Sellat nor anyone else can remove or alter it.

The fingerprint does not contain the file, does not allow it to be reconstructed and reveals neither its content nor its name. By creating a proof you expressly accept this publication and its permanent nature.

6. Qualified timestamp

When you request it, Sellat obtains a qualified timestamp issued by the FNMT-RCM, a qualified trust service provider, through its distributor, and incorporates it into your proof. Sellat acts as an intermediary: Sellat is not a qualified trust service provider.

A qualified timestamp enjoys the presumption of the accuracy of the date and time it indicates and of the integrity of the data to which it is bound (article 41.2 of Regulation (EU) No 910/2014). Only the file's cryptographic fingerprint is sent to the issuer, never the file.

If a paid seal is not issued because of a technical failure, we will refund its full amount; if it was to be paid for with an included seal or a seal from a pack, that seal goes back to your balance. The proof will have been created anyway and will remain valid without the seal.

7. Custody of the original file

Custody is an optional service, separate from the proof. If you turn it on for a file, we keep the original with a storage provider located in the European Union, with the encryption at rest that the provider applies, and we check that it matches the protected fingerprint when it is stored and every time you download it. You can delete it at any time.

Each plan has its own size limits, shown on the pricing page. If your subscription ends, your account returns to the free plan's limits; files already held in custody are not deleted for that reason without notifying you by email first.

Custody is not a backup service and does not replace your own copies: always keep the original yourself. The proof remains valid even if you delete the original or never deposit it.

8. Sharing links

You can create a link to share a dossier. Anyone who has the link will be able to see the name, size, fingerprint and dates of the files it includes, download their proofs and, if they are held in custody, view or download the original, subject to a daily download limit. Your email address is not shown.

You can hide files from the dossier or revoke the link at any time. Share the link only with people who should see it.

9. Connected shops

If you have an online shop, you can connect it to your account with the Sellat connector, available today for WooCommerce. From then on the shop sends Sellat a record of every paid order — amounts, lines, dates, the terms the customer accepted and a fingerprint of their email address, never the email address itself — and Sellat creates its proof. Sellat proves the record as your shop sends it: it does not check that the order details are true.

With the free account, each day's orders are proven together, in a grouped daily proof that is anchored after the day closes. With the Pro account, every order gets its own proof within minutes.

You can request a qualified timestamp for an order by hand, on any plan; with the Pro account, also through rules you set in the connector (for example, above an amount). Each seal is taken from your balance: the welcome seal, those from your packs and, with the Pro account, those it includes each month. If you have none left, the order keeps its proof and the seal stays pending; if it is issued later, it carries the date on which it is issued.

With the Pro account you can also turn on custody of a snapshot of each order: a full copy of the order as your shop stores it, which does include the customer's personal data, such as their name, addresses and phone number. It counts towards your plan's custody limits and you can delete it whenever you want. If you leave the Pro account, snapshots are deleted after 90 days, and we will email you 14 days beforehand; if you subscribe again before then, they are kept.

Order records, their proofs and the text of your shop's terms are kept for as long as your account exists, whatever your plan: they are what lets you prove each order later. You can disconnect the shop at any time by revoking its key from your dashboard; orders already recorded are not affected.

10. Your shop's customer data

As regards the personal data of your shop's customers that Sellat receives through the connector, you are the controller and Sellat acts as a processor on your behalf, within the meaning of article 28 of Regulation (EU) 2016/679, the General Data Protection Regulation. This section is the processing agreement between us and applies for as long as you have a connected shop.

Which data and why. Sellat processes that data only to provide the service in section 9: creating, keeping and verifying the proofs of your orders, issuing the seals you request and keeping the snapshots you turn on. It is the data in each order record — the customer's identifier in your shop, whether they are a registered customer or a guest, the fingerprint of their email address, the order details and, only if you turn it on, the IP address from which they accepted the terms — and, if you turn on snapshot custody, whatever each snapshot contains. The data subjects are your customers.

What Sellat undertakes to do. Process the data only on your instructions, which are these terms and the settings you choose in the connector, and not use it for any other purpose; ensure that anyone processing it is bound by confidentiality; apply technical and organisational measures appropriate to the risk, such as encrypted communications, restricted access to the data and integrity checks on what is kept in custody; help you, as far as it depends on Sellat, to respond to your customers' requests and to meet your security obligations; notify you without undue delay of any personal data breach affecting that data; and give you the information needed to demonstrate compliance with this article, and allow reasonable audits you request for that purpose, with prior notice.

Sub-processors. You authorise Sellat to use, to provide this service, the hosting, storage and site delivery providers listed in the Privacy policy; the provider that issues qualified timestamps receives only the fingerprint. Sellat imposes on them data protection obligations equivalent to these. We will email you about any change in those providers that affects your customers' data, and you can object by disconnecting the shop. Transfers outside the European Union, where there are any, rely on the safeguards described in the Privacy policy.

When it ends. If you disconnect the shop, Sellat stops receiving data and keeps what is already recorded as described in section 9. If you delete your account, the records and snapshots of your orders are erased; only the fingerprints published on public networks, which contain no personal data, and seals already issued remain. You can also ask us at any time, at hola@sellat.app, to erase the record of a specific order, knowing that from then on its proof cannot be presented together with it.

What is up to you. As controller, you must have a legal basis for the processing, tell your customers in your privacy policy that their order records are proven with Sellat as processor, and turn on the IP address or snapshots only when you have a reason to do so.

11. Prices and payment

The prices in force are those shown on the pricing page at the time of purchase. As of the date of these terms, VAT included:

Seals from a pack do not expire, accumulate in a single balance and are spent starting with the oldest pack, after those included with a subscription; packs require an account. If we were no longer able to issue qualified seals because the qualified provider stops providing the service, we will refund the proportional part of the price of the seals from your packs that you have not used. The annual Custody option and the Pro account can only be purchased when they appear on the pricing page. When the pricing page shows it as available, the API is included in your account with your plan's daily limits and, on the free account, with the grouped anchoring described in section 3; access for more volume is contracted on the basis of a quote, under specific terms. Payment is handled entirely through Stripe: Sellat neither receives nor stores your card details. Pay per call for software agents. The API also accepts pay-per-call with the x402 protocol, in USDC on the Base network, with no prior account or key: the paying wallet is the account, and the proofs and seals paid for are attached to it. Each payment offer (the HTTP 402 response) links these terms and states their version; making the payment constitutes acceptance of them by whoever controls that wallet, and Sellat keeps the accepted version with each payment. Prices on this channel are expressed in US dollars, taxes included, and are published at https://sellat.app/api/v2/x402; a call that cannot be served is not charged.

12. Subscriptions: renewal and cancellation

The Custody subscription is taken out monthly or yearly, and the Pro account monthly. Both renew automatically at the end of each period until you cancel them.

The annual Custody option credits 5 qualified seals to your account when you take it out and at each renewal; the monthly option does not include seals. The Pro account credits 3 qualified seals to your account with each monthly payment collected. Seals included with a subscription can be used for 12 months from the moment they are credited, also if you stop renewing; after that they expire. They are spent before those from your packs, starting with the ones that expire first.

The Pro account includes Custody. If you have Custody when you subscribe to the Pro account, Custody stops renewing as soon as the Pro account is paid, and the Custody period already paid for runs until its end.

If the Pro account ends, your account returns to the free account's limits and your shop's orders go on being proven, grouped by day, as on the free account. Files already in custody are not deleted for that reason without emailing you first.

You can cancel either of them at any time from your account, under «Manage the plan». Cancellation takes effect at the end of the period already paid for, during which you keep all the benefits of the plan, and does not give rise to a pro rata refund, except as provided for withdrawal.

If a payment fails, we keep the plan active for 7 days after the end of the period; once that time has passed, the account returns to the free plan. Returning to the free plan does not delete any proof already created.

13. Right of withdrawal

If you purchase as a consumer, you have 14 calendar days from the purchase to withdraw, subject to the following specifics.

Single qualified timestamp. When you buy it, you expressly request that the seal be issued immediately: it is issued at that moment by a third party and cannot be undone. For that reason, before paying, you accept that you lose the right of withdrawal once the seal has been issued (article 103 of the consolidated text of the Spanish General Law for the Defence of Consumers and Users). That acceptance is recorded together with your order.

Seal packs. Nothing is issued when you buy them, and you expressly request to be able to use the seals from that moment. If you withdraw within the 14 days, we will refund the part of the price corresponding to the seals you have not used. That request is recorded together with your order.

Custody subscription. When you subscribe, you expressly request that custody start from that moment. If you withdraw within the 14 days, we will deduct the part proportional to the time already enjoyed. For the annual option, the price of a single seal (6 €) will also be deducted for each included seal you have already used, because each one was issued by a third party and cannot be undone; the ones you have not used are not deducted. That request is recorded together with your order.

Pro account. It is an account for systems, teams and shops, so you will not normally take it out as a consumer. If you do, when you subscribe you expressly request that it start from that moment and, if you withdraw within the 14 days, we will deduct the part proportional to the time already enjoyed and the price of a single seal (6 €) for each included seal you have already used, because each one was issued by a third party and cannot be undone; the ones you have not used are not deducted. That request is recorded together with your order.

To withdraw, it is enough to tell us unequivocally at hola@sellat.app; if you wish, you can use the model withdrawal form provided for by law, although it is not mandatory. We will refund the amount due using the same means of payment within 14 calendar days at the latest.

14. Invoicing

Stripe emails you the receipt for each payment and issues an invoice for single seals and for the subscriptions. If you need an invoice for another purchase, or need the invoice to include your tax details as a business or professional, write to us at hola@sellat.app and we will send it to you.

15. Use of the service and third-party data

You are responsible for the content of the files you protect. You may not use Sellat to protect unlawful content, or to process third parties' personal data without a legitimate basis for doing so.

If the file contains health data or other special categories of personal data, bear in mind that the proof does not require uploading the file: when you are signed in, the fingerprint is computed on your device and the original does not leave it. Do not turn on custody for that kind of file unless you have assessed its processing yourself.

We may suspend an account that uses the service for unlawful purposes, in a way that compromises its operation for others, or to get around its limits, and withdraw any unused free benefits obtained that way; where necessary to protect the service, without prior notice. Proofs already created remain verifiable in any case, because they do not depend on your account.

16. Availability and liability

We make a reasonable effort to keep the service running, without committing to a specific availability percentage.

What we do guarantee is what gives the product its purpose: a correctly created proof remains independently verifiable, with public tools and without needing Sellat, even if Sellat were to cease to exist.

Nothing in the above excludes or limits liability that cannot legally be excluded towards consumers, or liability arising from wilful misconduct or gross negligence. Towards those who contract as professionals or businesses, our liability is limited to the amount paid for the affected service in the preceding twelve months.

17. Account closure and deletion

You can request the deletion of your account at any time by writing to hola@sellat.app. Doing so deletes your account, the files we hold in custody, the records and snapshots of your shops' orders and the personal data attached to your proofs.

Fingerprints already anchored and seals already issued remain: publication on a public network is irreversible, and the seal was issued by a qualified third party. It is also what lets the proofs you created remain verifiable by you after you close your account.

18. Data protection

The processing of your personal data is described in the Privacy policy, linked in the footer of every page.

As regards your shop's customer data, Sellat is a processor and section 10 applies.

19. Changes to these terms

We may amend these terms. If a change affects a service you have already purchased, we will tell you by email reasonably in advance, and you will be able to cancel it before the change takes effect. Proofs already created are governed by the terms in force when they were created.

20. Applicable law and complaints

These terms are governed by Spanish law.

You can send any complaint to hola@sellat.app and we will reply as soon as possible. If you purchase as a consumer, you may also go to the courts of your place of residence.

If you purchase as a professional or business, the courts and tribunals of Barcelona will have jurisdiction.