Proovik
Certify
Proof of existence and prior date · Verifiable time stamp

Prove that your document already existed at a specific date and time.

Proovik computes your file's fingerprint in your own browser and anchors it on the public Kaspa network. You get a proof of existence and prior date that anyone can check without an account and without trusting us.

Seal my first document free See a real certificate
  • Your file never leaves your device
  • Free account, no card
  • Electronic time stamp, eIDAS art. 3(16)
Seal now … free this month

Fill it in before dropping the document. It is not written to the chain.

Want to add a description or review the fingerprint before sealing? Seal step by step

File
SHA-256

Sent to the chain, pending confirmation Certified This document was already certified Could not be certified

It is not a certificate yet: it will be once the network confirms the transaction. Checked every 5 seconds.

The transaction is confirmed on Kaspa. You can now prove that the document with this fingerprint existed at the date and time shown.

SHA-256
TX
Download PDF PDF is issued on confirmation View on the explorer

The PDF includes the PVK-PROOF/1 proof: anyone can check it without Proovik. Verify it now

If you close the page, keep the fingerprint and the transaction id. Dropping the same file again shows its status without using quota.

Real example · 2026-09-20 Real example: a certificate issued by Proovik on 20 September 2026. 2026-09-20 00:03:00 UTC TX 174b1840…bbd1ff See the whole certificate
Who it is for

For when “I had it first” is not enough.

Lawyers and law firms

Minutes, drafts, exported emails, evidence. Seal the version you need to place in time and attach the certificate to the file.

How a date is proven

Creators and designers

Seal the sketch, the mockup or the song before showing it. If it turns up copied later, you have the date and the exact file.

Seal a file

Developers

One seal per artefact from your own system: deliverables, reports, releases. API with scoped keys and webhooks.

See the API

Companies with traceability

EPCIS 2.0 events from your supply chain with the same proof: who, what, when and where, checkable by your customer.

See traceability
How it works

Four steps. Zero uploads.

  1. 1

    Your browser computes the fingerprint

    A unique SHA-256 of the file, computed with WebCrypto on your machine. The file is not sent to anyone.

  2. 2

    The fingerprint is anchored on Kaspa

    It is written in the free field of a public transaction. Until the network confirms it, we say “pending” here, never “certified”.

  3. 3

    You get the certificate

    PDF with a QR code and the PVK-PROOF/1 proof package: fingerprint, transaction, block and Merkle path.

  4. 4

    Anyone can check it

    With your file and that package the whole chain can be recomputed, with or without Proovik. Try the verifier

Certificate PVK-PROOF/1

documento-de-ejemplo.txt

SHA-2560f7383b381366cc3a75dadd7e4a1e8998c492f7c5c5610f4384d7320f484aad8
Anchored2026-09-20 00:03:00 UTC
TX174b1840…bbd1ff
Real example · 2026-09-20

Real example: a certificate issued by Proovik on 20 September 2026.

PVK-PROOF/1 · Public verifier

If Proovik vanished tomorrow, your proof would still hold.

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 redo the check in any explorer.

  1. 1 · The transaction payload is the document digest.
  2. 2 · The transaction is committed in the block header.
  3. 3 · The header produces the declared block hash.
  4. 4 · A valid proof of work was executed over that header.
Verify a certificate Read the specification What a blockchain time stamp is
Certificate PVK-PROOF/1

documento-de-ejemplo.txt

SHA-2560f7383b381366cc3a75dadd7e4a1e8998c492f7c5c5610f4384d7320f484aad8
Anchored2026-09-20 00:03:00 UTC
BlockKaspa mainnet · 77ee3a38aecdb3d8e97a010f7f8f78927e48282d22ebfae3004713ba8a9d51fc
TX 174b1840fa7d0c8140aa585b1912cf7d1a9f4a6f8d6d2e4458caaa4ca2bbd1ff explorer
VersionPVK-PROOF/1
Real example · 2026-09-20 Verify this certificate

Original document (870 bytes) PDF certificate

Real example: a certificate issued by Proovik on 20 September 2026. The link returns the public verifier's verdict, with no account.

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.
  • That it has not changed by a single byte since: one different bit changes the SHA-256.
  • It is a non-qualified electronic time stamp (Art. 3(16)(i) of EU Regulation 910/2014) and, under Art. 41(1), admissible as electronic evidence.

It does not establish

  • Who authored the document, nor who sealed it.
  • That what the document says 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
The network

Why we anchor on Kaspa.

Confirmation in seconds

Kaspa uses a proof-of-work BlockDAG: the block that dates your document arrives in seconds, not hours.

Very low cost per anchor

Writing 32 bytes to the network costs little enough for a genuinely free plan to exist.

Public network, nobody rewrites it

The transaction can be looked up in any Kaspa explorer. Neither Proovik nor anyone else can change what is already mined.

How it compares with Bitcoin, OpenTimestamps and a qualified stamp
Pricing

Start free. Pay only if you seal a lot.

Free

Free

To try it out. No account, no card.

Professional ★ Recommended

€29/month

Certify without counting. Your whole history in one place.

API

€249/month

Seal from your own software.

Prices in euros, excluding VAT. Amounts and what each plan includes are on the pricing page; this page shows no figure that is not there. See pricing

Traceability

Batch traceability?

Proovik also records EPCIS 2.0 events from your supply chain with the same proof and publishes them as GS1 Digital Link. Agrifood, cold chain, pharma, manufacturing.

See traceability What EPCIS 2.0 is
Frequently asked questions

What people ask before sealing.

Do I have to upload my document?
No. Your browser computes the file's SHA-256 fingerprint and only those 64 characters travel to the network. The file never leaves your device, and its content cannot be reconstructed from the fingerprint.
Does it count as evidence in court?
It is a non-qualified electronic time stamp within the meaning of Art. 3(16)(i) of Regulation (EU) 910/2014. Under Art. 41(1) it cannot be denied legal effect or admissibility as evidence for being electronic or non-qualified; what it lacks is the presumption of accuracy of Art. 41(2), reserved for qualified time stamps. Weighing the evidence is always up to the court.
What if Proovik shuts down?
Your proof still stands. The fingerprint is written in a public Kaspa transaction, replicated across nodes that do not depend on us, and the PDF certificate carries the PVK-PROOF/1 package with everything needed to redo the check. The procedure is published: anyone can repeat it with standard tools.
Why Kaspa and not Bitcoin or OpenTimestamps?
Because confirmation arrives in seconds instead of hours, because the cost per anchor is low enough for a free plan to exist, and because it is a public proof-of-work network: the transaction can be looked up in any Kaspa explorer. OpenTimestamps is also a non-qualified stamp verifiable without its issuer; it anchors on Bitcoin and its proof completes when that transaction confirms.
How is it different from a qualified time stamp?
A qualified time stamp is issued by a supervised provider listed on the EU trusted list and enjoys the presumption of accuracy of Art. 41(2). Proovik's is not qualified: its date rests on the work of a public network, it can be checked without asking us for permission, and it does not replace an official register or a qualified provider.

All frequently asked questions

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