About this tool
What does it check?
Whether a PDF carries digital signatures, who claims to have signed, when, and whether the file changed since — the quick integrity sniff before trusting a “signed” document.
How to use it
- Drop the PDF in; signatures enumerate automatically.
- Read signer, timestamp and modification flags.
- Treat warnings as stop signs, not suggestions.
Examples
- Verifying a contract PDF before countersigning.
- Checking a downloaded form wasn’t tampered with.
- Auditing signed invoices in bulk.
Important limitations
- A pretty signature panel proves nothing by itself — chain to a trusted root matters.
- “Contains signatures” ≠ “valid signatures”: expired/revoked certs fail properly.
- For legal weight use qualified validation services, not a quick web check.
Privacy
Checked locally in your browser. Signed documents are often the most sensitive files you handle — they never leave this page.
Frequently asked questions
Valid signature but modified file?
Then it is NOT valid — any post-signature byte change breaks integrity by design.
Self-signed certs?
Technically verifiable, trust-wise meaningless without your explicit approval.
Multiple signatures?
Evaluated in order; later signatures cover earlier content plus prior signatures.