Verify PDF Signature
Find out who signed a PDF, when, and whether anything changed after signing. The check runs in your browser: the document is not uploaded anywhere.
Not checked here: whether the certificate issuer is on a trusted list and whether the certificate has been revoked. Both require contacting the issuer. Adobe Acrobat Reader checks them when it opens the file.
How to verify a signed PDF
- Choose the PDF.
- Each signature appears with its result: valid, changed afterwards, or invalid.
- Read who signed it and when, and download the signed version if the document changed later.
What "valid" means
A valid signature proves two things: the bytes of the document are exactly the ones that were signed, and the signature was made with the private key of the certificate shown. It does not, by itself, prove that the certificate belongs to a trusted provider: a self-signed certificate can carry any name, and the result says so when that is the case.
Changed after signing
PDFs are signed in layers: each signature covers the file up to that point, and later signatures, form data or comments are added on top. When a signature does not cover the whole file, you can download the exact version that was signed and compare it with what you received.
Is it private?
Yes. Everything runs inside your web browser, using your own device. Nothing is uploaded to any server, so your documents stay completely private. How does this work without uploading?
Frequently asked questions
Is my document uploaded?
No. The PDF is read and the signatures are checked with your browser's own cryptography. Nothing is sent anywhere.
Can it check a drawn or scanned signature?
No. A drawn signature is an image on the page; there is nothing cryptographic to verify. Only digital signatures made with a certificate can be checked.
Why does Adobe say the signer's identity is unknown when this says valid?
They check different things. This page checks that the document and signature are intact. Adobe also checks whether the certificate issuer is on its trusted list, which depends on the lists installed on your computer.