Check That a Signed PDF Was Not Changed

A free online tool for checking the integrity of a signed PDF. Upload the document and the verification seal it came with, and the tool confirms whether the file is unchanged since it was sealed — or warns you that it was altered.

How to verify a PDF

1
Upload the PDF

Choose the signed document you received.

2
Add the seal

Paste the verification code or upload the .seal.json file.

3
Verify

Press Verify and read the result.

4
Read the verdict

See whether the file is unchanged, was altered, or the seal is invalid.

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Confirm a signed PDF is exactly as it was sealed

1. Upload the PDF

The signed document you received.

Drop a document here or click to browse
PDF ·

No PDF selected yet.

2. Add the verification seal

Paste the verification code, or upload the .seal.json file that came with the PDF.

or

No seal added yet.

This tool checks file integrity only — it confirms whether a PDF was changed after a seal was created. The seal does not certify the signer’s legal identity; the name shown is the one the signer entered. For a legally binding electronic signature, use a qualified e-signature service.

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Features

Detect any change See who sealed it No account needed Works in your browser

Common uses

  • Confirm a signed contract you received was not edited on the way to you.
  • Check an invoice still matches the seal its sender created.
  • Spot a document that was re-saved or tampered with after signing.

What the seal proves — and what it does not

A verification seal proves tamper-evidence: it tells you the PDF is byte-for-byte identical to the one that was sealed. It does not prove who the signer legally is — there is no certificate authority involved, and the signer name is whatever the person typed. For an integrity check between two people who already trust each other, that is exactly enough. For a legally binding signature, use a qualified e-signature provider.

Frequently asked questions

What does a successful verification mean?

It means the PDF is identical to the one that was sealed — not one byte has changed. If anything had been edited, added or removed, the check would fail.

Is this a legal signature check?

No. This confirms file integrity only. The seal has no certificate authority behind it and the signer name is self-declared. For legally binding e-signatures, use a qualified e-signature service.

Where do I get the verification code?

The person who signed the PDF with the Sign PDF tool and enabled the seal receives a verification code and a .seal.json file. They share one of them along with the PDF.

Why does it say the file was changed?

The PDF no longer matches its seal. Common causes: the file was opened and re-saved by another program, edited, or it is not the exact file that was sealed.

Does the PDF need to be made with Timbrica?

The seal does. The PDF is signed and sealed with the Sign PDF tool; this tool then checks that PDF against its seal.

💡 Want us to improve this tool just for you?

We can — and it's free! Just send us a quick message with your idea. If you'd like to discuss it in detail, leave your email and we'll get back to you. You can stay anonymous.

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Who is this tool for?
✨ Content Creators 💻 Developers & IT Pros 🔒 Security & Privacy
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