AIssuance
Public verification · no account needed

Verify a document on the blockchain

AIssuance issuers anchor their documents — carbon verifications, contracts — on a public blockchain. This page exists so you don't have to take our word for it: check it yourself, against the chain, that the document in your hands is exactly the one that was sealed, and that it hasn't changed since.

Drop the document here or click to choose it

Your browser computes its sha256 instantly.

Your document never gets uploaded. The sha256 is computed inside your browser; the only thing that travels to our server is those 64 characters. We don't receive the file, don't store it, and can't reconstruct it from the hash.

or paste the hash

How it works

1. The document's fingerprint is computed

Every document has a unique 64-character digital fingerprint — its sha256. Changing a comma, a signature, or a decimal produces a completely different fingerprint.

2. That fingerprint was written to the blockchain

When an issuer anchors a document, it publishes only its fingerprint to a public network (Polygon). It lands in a block with a timestamp, visible to anyone, editable by no one — not even us.

3. You compare, you don't trust us

Here you recompute the fingerprint of your own copy and check whether it matches an anchored one. If it matches, your copy is identical to what was sealed that day. If not, something changed.

Compute the sha256 yourself

If you'd rather not use our form even to compute the fingerprint, your own operating system can do it. Paste the result above afterward — or compare it by eye against the one on the receipt.

Windows (PowerShell)

Get-FileHash .\document.pdf -Algorithm SHA256

macOS / Linux

shasum -a 256 document.pdf

Windows (cmd)

certutil -hashfile document.pdf SHA256

What a verification does — and doesn't — tell you

An anchor proves existence on a date and integrity since then: that file already existed that day and wasn't altered afterward. It doesn't certify that its content is true, or that a third party audited it. It's a timestamp on the file, not a judgment on what's inside it.