What is Tamper-Evident Seal?
A cryptographic seal that makes any change to a document detectable after it is signed.
A tamper-evident seal binds a document to a cryptographic fingerprint (SHA-256) at the moment of signing. Because the hash changes completely if even one byte is altered, anyone can re-compute it and compare against the published value to prove the document is unmodified. Unlike a physical wax or rubber seal, a digital tamper-evident seal is verifiable remotely, by anyone, with no special tools, and PDF Verified pairs it with a public QR verification page and an append-only audit trail.
Design your company stamp or seal now. Round seals, dated stamps and approval marks, with a date that fills itself in and a serial number that never repeats. Free to design, and it goes straight onto a PDF, a Word file or an Excel sheet.
Lady Justice (THEMIS), Legal
Medical seal (caduceus), Medical
Gold certificate seal, Business
Wax seal, Legal
How a tamper-evident seal works
At signing, PDF Verified hashes the exact document bytes with SHA-256 and records the value on a public verification page, with a visible seal mark on the PDF. To verify, re-hash the file: a match proves integrity; a mismatch proves tampering.
Seal vs signature vs stamp
The signature captures intent, the stamp conveys authority, and the tamper-evident seal proves the file has not changed since. Together they make a document both authoritative and verifiable.
What PDF Verified is, and what it is not
These checks are a screen, not a verdict. A clean result means nothing was found by the checks that were run, which is not the same as proof that a document is genuine, and a flagged result can have an innocent explanation such as a re-save or a scan. Read the findings rather than the headline, and where a decision carries real consequences, confirm the document with the party that issued it. It is a tool for examining a document, not for producing a forged or altered one.
PDF Verified is a tool for preparing, signing, stamping and checking documents. It is not a law firm, a compliance service or a forensic examiner, and nothing here is legal, financial or compliance advice. Requirements differ by country, by document type and by the party asking, so check what applies to your document before you rely on it, and take advice where the document matters. You are responsible for the documents you create, sign and send, and for having the authority to do so: signing or stamping in somebody else name, or as an organisation you do not represent, is forgery whatever tool is used. To the extent the law allows, we accept no liability for how a document made with this tool is used or relied on. The full position is in our terms of service.