Verify PDF Signature
Check the digital signatures in a PDF: who signed it, when, and whether the document was changed afterwards. Runs entirely on your device.
About this tool
Verify a PDF Signature — See Who Signed and Whether the File Changed
Check every digital signature in a PDF: who signed, the certificate, the timestamp and whether the file changed after signing. Nothing is uploaded.
Integrity, Checked Cryptographically
For every PAdES or PKCS#7 signature, Toolula hashes the signed byte ranges, compares them with the digest inside the signature and verifies it with the signer's public key — the same integrity test a PDF reader runs.
Every Detail in One Place
Signer and issuer, certificate validity, self-signed certificates, the RFC 3161 timestamp and its authority, reason and location, and whether anything was added to the file after a signature.
Private by Design
Contracts, offers and certificates stay on your device: nothing is uploaded, and the check keeps working offline once the page has loaded.
How to use it
- Drop the signed PDF.
- Read the report: each signature shows Intact, Broken or Not checked, with the signer, the certificate issuer and its validity.
- Check the time: a trusted timestamp names its time-stamp authority; otherwise the time comes from the signer's own clock.
- Look at the coverage line. "File changed after this signature" means something was appended later, such as another signature or a filled-in field.
- Need to add your own signature? Click Sign this PDF too and open your .p12 or .pfx certificate.
Frequently asked questions
What does "Intact" mean?
The bytes the signature covers are exactly the ones that were signed, and the signature value matches the signer's certificate. If a single byte of the signed content had changed, the signature would show as Broken.
Why does Acrobat say "validity unknown" when Toolula shows Intact?
Integrity and trust are separate questions. Acrobat also asks whether the certificate chains to the Adobe Approved Trust List or the EU Trusted Lists. Self-signed, test and in-house certificates prove the document is unchanged, but not who signed it.
Does Toolula check revocation or the EU Trusted Lists?
No. That needs online lookups (OCSP, CRL) and a trust store. When a qualified signature has to hold up formally, also check the file in your PDF reader or with the EU's DSS validation service.
"File changed after this signature" — is the document forged?
Not necessarily. PDFs are signed incrementally, so a second signature, a filled-in form field or a comment added later is appended after the first signature. The first signature stays intact for the part it covers; what was added afterwards is not covered by it.
My PDF shows a signature, but Toolula finds none. Why?
A signature drawn by hand, pasted in as an image or scanned from paper is only a picture on the page. Only cryptographic signatures stored in a signature field can be verified.
Are my PDFs uploaded to a server?
No. Toolula processes the document inside your browser tab with pdf-lib and WebAssembly, so the file never leaves your device.
Is it really free?
Yes. You can use every Toolula PDF tool for free, without an account. The free plan has fair-use limits; Toolula Pro, an optional plan, raises them and adds advanced features.