Terms of Service

Existence Anchor is operated by SynthThinkers, s.r.o., Nové sady 988/2, 602 00 Brno, Czech Republic; company ID 21010404, registered at the Regional Court in Brno, file C 136846 (“we”). These terms apply to everyone who uses Existence Anchor: its website, its app and its API.

Your browser, or through the API your own software, computes the SHA-256 digest of a file you choose and sends us only the digest, with a label if you add one: the file itself never reaches us. We add a random nonce and send the resulting blinded value to timestamp servers that use the OpenTimestamps protocol, which anchor it in a Bitcoin block. Once that block has enough confirmations, we check it and issue a certificate, as your plan allows. You can download each stamp’s receipt, its .ots proof and, once issued, its certificate.

A stamp proves one thing: the document with this SHA-256 digest existed no later than the time of Bitcoin block N (its timestamp, ±~2 h miner tolerance), independently verifiable against the Bitcoin blockchain without trusting us. It does not show who wrote the document, who owns it or whether what it says is true. It is a technical record for independent verification, not a legal document. Whether a court or authority accepts a stamp as evidence is for that court or authority to decide.

Bitcoin settles by probability: in principle, a reorganisation of the chain could replace a block. A certificate is issued only once its block has enough confirmations, and it states how many it had.

You need an account to make stamps, and you confirm its email address before your first stamp. Keep your password and API keys secret: what is done with them counts as done by you. If you use Existence Anchor for a company or another organisation, you accept these terms on its behalf. The contract is in English. It is made when you create an account, and for a paid plan when you complete Checkout. We keep no separate copy of it for you: save or print these terms.

Every account has exactly one admin, who can turn it into an organisation, invite members by email up to the plan’s limit (an invitation’s link works for 7 days), remove members and hand the admin role to another member. Only the admin manages the plan and payment. The plan, its limits and the stamps belong to the account, not to the member who made them: every member sees every stamp, and a member’s stamps stay with the account when the member is removed or deletes their own account.

The plans, with their limits and prices, are on Pricing.

The Free plan costs nothing. Paid plans are subscriptions, paid in advance through Stripe in US dollars, that renew automatically until cancelled. Checkout asks you to request an immediate start and to confirm that you thereby lose your 14-day right of withdrawal; a subscription cannot be started without it. Payments are not refunded.

How subscriptions renew, change, are cancelled and end, and what then happens to your stamps, is set out in Refunds and cancellation, which is part of these terms.

Do not use Existence Anchor to break the law, to reach accounts or data that are not yours, or to overload the service or get around its limits, and do not test its security without our written permission. We never see your files, only their digests, so we do not check what you stamp: what your documents contain is your responsibility.

We work to keep Existence Anchor running, but we do not promise that it is always available or free of errors. Anchoring depends on the timestamp servers and on the Bitcoin network, which we do not control, so how long it takes is not up to us. We may change the service and its features. If the service does not work as these terms describe, tell us at support@existenceanchor.com; if you are a consumer, you keep the rights the law gives you when a digital service is faulty.

We store each stamp’s .ots proof and certificate for the time the Privacy Policy states, then delete them together with the stamp’s label. A .ots you downloaded once the stamp was anchored keeps verifying without us: keep it with your document.

As far as the law allows, we are not liable for indirect loss, such as lost profit, and our total liability to you is limited to what you paid us in the 12 months before the claim. These limits do not apply where the law forbids them, for example to harm caused intentionally or by gross negligence, and they do not take away your rights as a consumer.

We may disable a user’s sign-in if they break these terms, if their use puts the service or other people at risk, or if the law requires it. While it is disabled, they cannot sign in, and their sessions and API keys do not work. If you think we made a mistake, write to support@existenceanchor.com.

You may stop using Existence Anchor at any time. Deleting your account in the app (Team → Delete your account) signs you out everywhere, cancels a paid subscription at once when you are the account’s only member, with nothing refunded, and erases your account after 7 days unless you keep it with the link in the email we send. An organisation’s admin with other members first makes another member the admin, or removes the others. If you leave an organisation whose subscription is paid with a card you entered, it keeps paying with that card until its admin replaces it. What is erased and what stays is set out in the Privacy Policy.

We may change these terms. Each new version is published on this page with the date it was last updated. If you do not accept a change, you can cancel your subscription and delete your account.

These terms are governed by Czech law, and disputes go to the Czech courts. If you are a consumer, you keep the protection the law of your country gives you, and if you live in the European Union, you may take a dispute to the courts where you live; you may also take it to the Czech Trade Inspection Authority (Česká obchodní inspekce, coi.gov.cz), which settles consumer disputes out of court.

Questions about these terms: write to support@existenceanchor.com.