Proovik
Certify
Seal a document · Free to start

Certify that this document existed today.

Your file is not uploaded: your browser computes its SHA-256 fingerprint and only that fingerprint, 64 characters, is anchored on Kaspa. You get a proof of existence and prior date that anyone can check without an account.

  • Your file never leaves your device
  • Free account, no card
  • Electronic time stamp, eIDAS art. 3(16)

… free certifications this month, in this browser.

See pricing

You have used this month's free certifications

The free quota is three per month and per browser, and it renews next month. What you already sealed stays anchored and verifiable: that does not expire. If you need more now, create an account or look at the plans.

Create a free account See the plans
1
Step 1 · Your file

Drop a file or click

Your document does not leave your device: only its fingerprint is computed. Neither Proovik nor anyone else receives the file, just the 64 characters of the SHA-256.

2
Step 2 · Fingerprint computed

Seal on Kaspa

As soon as you drop the file you will see its SHA-256 fingerprint here and you will be able to add a description and an email before anchoring it.

Fingerprint computed on your device

SHA-256

Stored only at Proovik and printed on your PDF; it is not written to the chain.

So we can send you the certificate and you can recover it. It is not written to the chain and does not appear on the PDF.

No card and no password. Pressing sends the fingerprint to the chain.

3
Step 3 · Your certificate

Anchored and checkable

The fingerprint, the date, the block and the transaction will appear here, along with the PDF and the link to the public verifier.

Sent to the chain, pending confirmation This document is now sealed on Kaspa This document was already certified Could not be certified

The transaction has been issued. It is not a certificate yet: it will be once the network confirms it. This page checks every 5 seconds.

The fingerprint is anchored and confirmed on the public Kaspa network. Anyone can check it without trusting Proovik.

Its fingerprint was already anchored since the date shown. No free certification was used.

Download the PDF certificate PDF is issued on confirmation Verify it yourself View on the explorer

We also send the certificate to the email you gave, with the PVK-PROOF/1 proof file attached.

If you close this page, keep the fingerprint and the transaction id. Dropping the same file again shows its status and, once confirmed, the PDF; checking does not use quota.

Privacy

What leaves your browser. And what does not.

Leaves

  • The SHA-256 fingerprint: 64 characters. It is the only thing written to the chain.
  • The description and the email, if you fill them in: they are stored at Proovik to issue and send you the PDF, and are not written to the chain.
  • A browser identifier used to keep track of the free seals.

Does not leave

  • The file. It is read in memory to compute its fingerprint with WebCrypto and is not sent to any server.
  • Its name and its content: the name is only used to label the certificate on your screen and on the PDF.
  • Nothing that allows reconstructing the document from what is published: a SHA-256 cannot be reversed.
Scope

What a Proovik seal establishes. And what it does not.

It establishes

That that exact file existed at the date and time shown by the block, and that it has not changed by a single byte since. It is a non-qualified electronic time stamp (Art. 3(16)(i) of EU Regulation 910/2014), admissible as electronic evidence under Art. 41(1).

How a date is proven

It does not establish

Who authored the document, who sealed it, or whether its content is true. It is not a qualified stamp: it lacks the presumption of accuracy of Art. 41(2) and does not replace a qualified provider or an official register. Weighing it is up to the court.

Legal questions, with the regulation cited
Frequently asked questions

Before you seal

All frequently asked questions

Is my document uploaded?
No. Your browser computes the SHA-256 fingerprint and only those 64 characters travel to Kaspa. The document cannot be reconstructed from the fingerprint, by us or by anyone.
Does it count as evidence in court?
It is a non-qualified electronic time stamp (Art. 3(16)(i) of EU Regulation 910/2014), admissible as electronic evidence under Art. 41(1). It establishes the file's existence and prior date; weighing it is up to the court.
And if Proovik disappears?
The proof lives on the Kaspa network, not on our servers. The format is documented and the verifier is public: with your file and your proof file, anyone can check it.