Free Online PDF Signature Verification

This tool allows you to verify the validity of electronic and digital signatures in PDF documents and detect whether the file has been modified after signing. Validation is based on internationally recognized PDF signature standards such as PAdES and X.509 certificates. All verification is performed locally in your browser. Files are never uploaded, stored, or logged.

Select or drag a PDF file to validate its signatures

Supports PDF format, maximum file size 10MB

How to Verify a Signature in Three Steps

No account, and no upload to our servers — the file is checked locally in your browser.

Upload the signed PDF

Drag the file in, or select it from your device. Files up to 10 MB are supported.

The signature is read automatically

The tool extracts the embedded signature, certificate details and the timestamp source.

Read the result

You get a plain-language verdict: unchanged or modified, who signed, and when.

What the Verification Report Shows

Each check answers a different question about the signature inside the file.

What we check	What it tells you	Why it matters
Document integrity	Whether the file changed after it was signed.	An altered document fails the check, even if the signature block still looks intact.
Signer certificate	Who the certificate was issued to, and by which authority.	This is how you confirm who actually signed the document.
Certificate validity	The period in which the certificate was valid.	A signing time outside that window is a warning sign worth investigating.
Timestamp source	Whether a trusted authority recorded the signing time.	It proves when the document was signed, not just when it was uploaded.
Signature algorithm	The cryptographic method behind the signature.	Older algorithms offer weaker protection as computing power grows.

Understanding PDF Signature Verification

Definitions and result meanings that come up most often when you check a signed PDF.

What information can I verify with this tool?

You can verify whether electronic and digital signatures in a PDF are valid, view the signature algorithm, signing time, certificate details, trusted timestamp information, and check whether the document has been modified after signing.

What is a signature in a PDF electronic signature system?

In a PDF electronic signature system, a signature is encrypted data embedded in the document. It is used to prove that a signing action occurred and that the document can be verified for integrity and authenticity.

What is a digital certificate?

A digital certificate is an electronic credential issued by a trusted Certificate Authority (CA). It binds the signer’s identity to their public key and usually conforms to the international X.509 standard.

What does “Modified” mean in the verification result?

Modified means the file has been changed after signing, and the original signature can no longer guarantee the integrity of the document.

What does “Signature Invalid” mean?

Signature Invalid means the file contains a signature, but verification failed. This may be caused by document tampering, an expired certificate, or an untrusted certificate chain.

What does “No Signature Found” mean?

No Signature Found means the document does not contain a signature that meets PDF signature standards, or the signature algorithm or format cannot be recognized.

More tools and resources

Need to create something instead? Create an electronic signature, sign a PDF online, or make a digital stamp — all free in the same browser toolkit.

Checking signatures at work? eSignature features cover identity checks, audit trails and tamper-evident sealing, and the eSignature platform applies them to every agreement.

For background reading, see how digital signatures are created, why signed documents stay authentic, and the legality overview.

Frequently Asked Questions

Have questions about PDF signature verification? Find answers below.