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Cryptographic verification

Verify a signed document

Confirm a SignLab-signed PDF is authentic and unchanged since the moment it was signed. Processed entirely in your browser — your file never leaves your device.

Drop your signed PDF here
or click anywhere in this area to browse
Computing SHA-256 fingerprint…
SHA-256 cryptographic check Never uploaded Result in 1 second
0 / 10

10-character code printed on the signed PDF, next to the QR code or in the footer.

0 / 64

Paste a 64-character hex hash. Compute locally with sha256sum document.pdf on macOS / Linux.

Behind the scenes
How verification works
01

Fingerprint

When the document is signed, SignLab generates a SHA-256 fingerprint and stores it on our servers.

02

Compare

Your browser computes the fingerprint of the file you submit and sends only that — not the file itself.

03

Result

A match means byte-identical to the signed version. A mismatch flags any tampering.

Only document metadata is shown on the result page — signed PDFs require authentication to download.