Document fraud prevention: tamper-proof signatures & verifiable stamps

Drop your document here and sign it now. PDF, Word and Excel all work: a .docx or .xlsx is laid out in your browser exactly as it was written, so there is nothing to convert first. Add a signature, a date, a company stamp or a watermark, then download it sealed. Free to start, no account, and the file is never uploaded to open it.

Document forgery jumped 244% last year and identity-fraud losses topped $50 billion. PDF Verified makes every signed document fraud-resistant by design, cryptographically sealed, publicly verifiable by QR, and backed by a tamper-evident audit trail and serialized, revocable stamps. If a single character changes after signing, verification fails.

The four layers of tamper-evidence

• Cryptographic seal (SHA-256), the hash breaks on any change, proving integrity.
• Public QR verification, a no-login page shows status, hash, signers, and stamp validity.
• Serialized, revocable stamps & seals, unique token + serial per use exposes reuse; revoke to withdraw trust.
• Tamper-evident audit trail, who signed, when, from what IP and device; append-only chain of custody.

How verification works

1. Seal at signing. A SHA-256 fingerprint of the exact content is computed and a tamper-evident seal mark is stamped.
2. Publish a verification record. A public QR-linked page is created with the hash, signers, timestamps, and any serialized stamps.
3. Anyone verifies in seconds. A recipient scans the QR to confirm the document is genuine and unaltered and that stamps are valid.

Free forensic checks on any PDF, even ones we didn't seal

You also receive documents other people created, invoices, bank statements, receipts, contracts, that were never sealed on PDF Verified. For those, our free, read-only forensic tools catch the fakes a glance never would:

• Bank-statement balance check, we re-add the running balance and flag the exact row where the maths stops adding up, the tell-tale sign of a doctored figure that structural checks miss.
• Structural forensics, edits after signing, incremental updates, mismatched producing tool and changed file IDs, with an advisory risk rating on any PDF.
• AI-generation & Content Credentials, reads C2PA Content Credentials and AI-tool markers to flag documents produced or altered by generative AI.
• Batch screening, drop a whole stack of PDFs and screen them together in one exportable table, built for lenders, landlords and finance teams.

These forensic signals are advisory and layout-dependent; a cryptographic hash match against a sealed original remains the only definitive proof of authenticity.

Built for high-fraud, high-trust documents

Contracts, invoices, prescriptions, certified true copies, title deeds, affidavits, bank letters and company resolutions, anywhere a forged document or fake stamp causes real loss. Compliant with ESIGN, UETA and eIDAS.

Frequently asked questions

How do you prevent document fraud and forgery?

PDF Verified prevents document fraud with four layers: a SHA-256 cryptographic hash that breaks if a single character changes, a public QR verification page on every signed document, serialized stamps and seals that are independently verifiable and revocable, and a tamper-evident audit trail recording who signed, when, from what IP and device. Any alteration after signing is immediately detectable.

How can I verify a document is genuine and not altered?

Scan the QR code on the signed PDF (or open its /verify link). The public verification page shows the document status, the SHA-256 fingerprint, the signer list and timestamps, and whether any applied stamp has been revoked, so anyone, with no account, can confirm the document is authentic and unmodified.

How do you detect a forged or altered PDF?

Each sealed document is fingerprinted with SHA-256 at signing. Re-hashing the file and comparing it to the value on the public verification record reveals any change, even one byte, because the hash will not match.

How do you stop signature forgery?

Signatures are captured with intent, timestamp, IP and device, then bound to the document by the hash and stored in an append-only audit trail, so a copy-pasted signature fails verification.

How do you prevent stamp and company-seal fraud?

Every stamp applied through PDF Verified mints a unique verification token and optional serial number; scanning confirms it is genuine, shows its document, and reveals if it has been revoked, exposing photographed or reused stamps.

Is a PDF Verified document admissible as evidence?

Yes. PDF Verified complies with ESIGN, UETA and EU eIDAS; the SHA-256 seal, audit trail, and certificate of completion provide tamper-evidence and chain of custody to support admissibility in most jurisdictions.

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.