Verify PDF Signatures
Check who signed a PDF and whether it changed.
Secure cloud processing
Verify a digital signature in a PDF on your phone or computer before you rely on it. See who signed and when, whether the document was modified after signing, and whether the certificate is trusted.
How to verify a digital signature in a PDF
- 1Select a signed PDF.
- 2Wait for the check to finish.
- 3Review the signer, signing time, document status and certificate.
Why Sahl PDF?
- Shows the signer's name and signing time
- Detects changes made after signing
- Distinguishes valid from untrusted certificates
- Encrypted upload, deleted immediately
Frequently asked questions
How do I know if a PDF is digitally signed?
Select the file and the tool lists any digital signatures it contains, or tells you there are none.
What does valid but untrusted certificate mean?
The signature is technically intact, but the certificate wasn't issued by a known trusted authority — for example, a self-signed certificate.
Does it detect changes after signing?
Yes. It shows whether the document is unchanged or was modified after it was signed.
Can it verify a drawn signature image?
No. It checks certificate-based digital signatures only; a signature image carries no data that can be verified.
Is verifying a PDF signature free?
Yes. You can verify signatures free 3 times a day without signing up.
Can it check a PDF with several signatures?
Yes. Every digital signature in the file is listed with its own signer, time and status.