Verify Digital Signatures in a PDF

Choose the signed PDF. Every digital signature in it is listed with a coloured verdict saying whether the document has changed since that person signed, along with who the certificate belongs to, who issued it, whether it has been revoked and when it was signed. You can download the result as a PDF report.

What you see is a picture of a signature, drawn, typed, scanned or stamped onto the page. This tool checks for a different kind: a digital signature made with a certificate and stored inside the file. A PDF can show a signature and contain none. Our article "What is a digital signature in a PDF" explains the difference.

We looked for things that look like a signature but are not a digital one: pictures shaped like a signature, hand-drawn marks, stamps, and signature fields that were prepared but never signed. We name the page so you know what we mean. It is only a hint. We can't tell whose signature a picture shows.

It is the short answer. Green means the document is unchanged since that person signed it; if it adds "only permitted additions", someone later filled in a form field or added another signature, which the first signature allows. Amber means the file was changed after signing. Red means the signature is broken, or the certificate used for it has been revoked. The lines below give the detail.

When the file was changed, the result lists each change, for example "Page 1: the page content was changed" or "Page 2: a comment was added". "Compare the changed pages" then shows each of those pages as it was signed and as it is now, side by side. The pictures are drawn in your browser.

Yes, when something was added after a signature. "Download the version that was signed" gives you the file exactly as that person signed it, before any later changes. It is taken from the file you chose, in your browser, and nothing extra is uploaded.

Who the certificate was issued to, who issued it, its serial number, the dates it is valid between, what it may be used for, its SHA-256 fingerprint and the chain of certificates above it. To be sure a certificate belongs to someone, ask them for its fingerprint and compare the two.

Yes. "Download report (PDF)" saves everything on the screen: each signature's result, every check, the changes after signing and the certificate details, with the file's name, size and SHA-256 fingerprint. The report describes what the check found. It is not a signature itself and doesn't certify the document.

It was probably printed to PDF, flattened, re-saved or edited after signing. Those steps rebuild the file and can keep the picture of the signature while removing the digital signature itself. Ask the sender for the original signed file.

It means the document hasn't changed at all since it was signed. This is the most important line in the report.

That the document was changed after it was signed, or the signature itself is damaged. Do not rely on its contents without checking with the sender.

No. It means this checker doesn't recognise who issued the certificate. That is very common for certificates a company gives its own staff. If Signature says Valid, the document hasn't changed since signing. Trust is a separate question about who vouches for the signer.

Whether Adobe Acrobat would show a green tick for this signer. Only Adobe can say that for certain, because it depends on Adobe's own list of approved certificate authorities, so this tool reports it as not verified rather than guessing.

Whether the certificate's issuer has cancelled it, usually because it was lost, stolen or issued by mistake. The check asks the issuer directly. "Not checked" means the certificate names no such service, or it couldn't be reached. It is not a failure.

Something was added to the file after it was signed, for example a comment, a form entry or a later edit. The signed part is still intact, but whatever was added afterwards is not covered by any signature. The list under that signature says what was added, and on which page.

Yes. Any standard PDF digital signature can be checked, whichever program made it. Every signature in the file is listed separately, with who signed and when.

Yes. Every tool works without paying and without an account. Files can be up to 200 pages and 80 MB, and a run that fails costs you nothing.

No. All tools work without signing in. An account raises your hourly allowance and lets you see what you have processed.

Your file stays on our server only for a short time while it is processed, then it is deleted. It is sent over an encrypted connection. We keep a record that the tool was used, but not the file name or what is in the file.