Choose your work
any file, up to 1 GBDrag the file here, or click to choose it
Any format — the fingerprint is computed in your browser, the file is never sent
Describe the work
optionalAdd title, author, year and notes — they'll appear on the certificate
This data appears on the certificate as the author's declarations and is bound to the security signature: it can't be changed after issuance.
Generate the attestation
Have an agreement or a Professional subscription? Sign in with your email
If your academy, institution or company has an agreement with Spazio Genesi — or if you have a Professional subscription — verify your email: attestations will be automatically recognized under your tier, with a stronger guarantee of certificate custody. No password, no account: a single one-shot sign-in, valid for this browser session.
✓ Your work is attested
| Work | |
| Date and time | |
| Issued by |
Technical details (size, attestation string)
| Size | |
| File type |
The PDF certificate is the document to keep, together with the original file of the work.
Tip: send it to yourself by registered/certified mail — add legal proof of possession to the mathematical proof.
Choose the file to check
Drag in the file you received, or click to choose it
it must be the original file, not the PDF certificate
Open the PDF certificate
Drag in the PDF certificate, or click to choose it
we read its fingerprint, signature and declared data
Don't have the PDF certificate? Enter the fingerprint manually
Advanced verification: security signature and declared data (from the certificate)
Data declared on the certificate (only if present)
Verification result
Technical details of the verification
Blockchain verification (OpenTimestamps) — how to
Certificates issued from version 1.7 onward anchor the work's fingerprint in the Bitcoin blockchain via the open OpenTimestamps protocol: proof of existence independent of our servers, which no one can backdate.
-
Get the
.otsproof: download it from the link that appears after "Download the PDF certificate", from the address printed in the certificate's "Technical details", or — if you entered the declared hash above — download it for the entered hash. - Go to opentimestamps.org, the Stamp & verify panel.
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Drag the
.otsfile into the panel, then, when asked, the original work (the exact file you attested). - Expected result: "Bitcoin attests data existed as of …" with the date guaranteed by the blockchain. In the first hours after issuance you may see "Pending confirmation": the final confirmation matures with the Bitcoin block.
Verification works offline too, and decades from now: the proof depends only on the
.ots file, the original work, and the public Bitcoin blockchain.
Lost your certificate?
We keep a copy of every certificate issued. Choose the original file of the work above (or enter its fingerprint) and re-download your signed PDF certificate, identical to the original.
This service generates the digital fingerprint of your work — any file, up to 1 GB — and ties it to a certain date with a signed PDF certificate. The fingerprint is computed directly in your browser: the file never leaves your device. By keeping the attestation you'll always be able to prove that exactly that file existed, unchanged, at that moment: useful before publishing, entering a competition, or delivering a draft.
How to use it — three steps:
- Drag the file into the «Attest» tab.
- Your browser computes the fingerprint (the file stays on your device): download the PDF certificate (or the .txt) and keep it.
- At any time, verify: drag the file again into the «Verify» tab and the service confirms it's identical.
Video guide — the whole service in under two minutes:
The guarantees, in brief
Each line is a benefit: open it to read how it works and how to verify it.
+A unique digital fingerprint
A 64-character code identifies your file uniquely — it can't be repeated by chance.
The fingerprint (SHA-256 hash) is computed on the exact bytes of the file: change just one pixel — or one comma — and the fingerprint becomes completely different. That's why it proves the file hasn't been modified.
It works with any format: images, video, audio, documents, 3D models, archives.
+Total privacy: the file never leaves your device
The fingerprint is computed in your browser: only the code reaches us, never the work.
The fingerprint is computed directly in your browser (WebCrypto technology, a web standard): the work is never sent to our servers, which receive and attest only the fingerprint. This holds for both attestation and verification.
How to verify it: the service's code is open source: anyone can check that the file is never sent (for example by watching the browser's network traffic during attestation).
+A certain date, guaranteed by a third party
The issuance date is certified by an independent authority recognized by Adobe.
The PDF certificate includes a timestamp issued by DigiCert, an authority on Adobe's trust list: we don't declare the date ourselves — a third party attests it.
How to verify it: open the PDF in Adobe Acrobat → Signatures panel → "The signature includes an embedded timestamp."
+Anchored in the Bitcoin blockchain
The fingerprint is also recorded on Bitcoin: no one can backdate it, not even us.
When you generate the certificate, the fingerprint is recorded in the Bitcoin blockchain via the open OpenTimestamps protocol: proof of existence that doesn't depend on our servers.
How to verify it:
- Download the
.otsproof file (the link appears after "Download the PDF certificate"). - Go to opentimestamps.org, the Stamp & verify panel.
- Drag in the
.otsfile and the original work: you'll get "Bitcoin attests data existed as of…".
The final confirmation matures within a few hours of issuance.
+Your work is not kept
The file is used only to compute the fingerprint: it's never stored or handed to anyone.
The file is processed in memory for the time it takes to compute its fingerprint, then discarded: it's never saved, nor handed to third parties, nor used for any other purpose. In our archives, only the PDF certificate — which contains the fingerprint, not the work — and the blockchain proof remain.
+Data stored in Europe (EU)
The certificate and proof stay on infrastructure with data residency in the European Union.
The PDF certificate and the proof of existence are stored on Cloudflare R2 in the European Union jurisdiction: the data physically stays in the EU, in line with the GDPR. The work itself, as noted, isn't kept in any case.
+Open code, verifiable by anyone
All the service's code is public: you don't have to take our word for it.
"Open source" means the code that runs the service is published in full: anyone — even an expert you trust — can read it and verify it does exactly what it claims, including the promises about not keeping files. We don't ask for your trust: we demonstrate it.
The cryptographic keys aren't in the code: publishing it doesn't weaken anything.
+Free verification, forever, for anyone
Anyone who receives your certificate can check it in one click, with no registration or payment.
Every certificate contains a QR code and a link that open this page with the fingerprint already filled in: whoever receives it drags in the file and gets the result right away. Verification will always stay free and open to everyone — that's what gives the certificate its value.
+Signed PDF certificate
Every attestation produces a digitally signed certificate, with a verification QR code.
The certificate is digitally signed by Spazio Genesi ETS with a valid but self-issued certificate (issued by the association itself): the date is already guaranteed by the third-party timestamp and by the blockchain. In the future the service may evolve with a recognized electronic seal for the issuer's identity too.
If you declared a title, author, year or notes, this data is "sealed" into the security signature: no one can change it after issuance.
Real-time service status and 90-day history: status page.
Prefer to stay inside Telegram? The bot @SGAttestBot attests and verifies there too — it's a convenience channel, not full-privacy like the site: the file you send it passes through Telegram and our server (the fingerprint is computed right away and the bytes are discarded, nothing is saved). For absolute privacy, use the site.