Identify a file by its magic bytes and flag extensions that lie about the real format.
New
PDF Signature Detector
Runs locally
Use PDF Signature Detector
What it does
Choose a PDF to see whether it contains digital signature markers (/ByteRange and /Sig) and any signer name, reason and location stored with them. It does not validate the signature or the certificate.
It runs entirely in your browser: nothing you enter is uploaded.
Example
A digitally signed PDF
A PDF signed with a digital certificate, chosen with Upload PDFFound 1 signature marker(s)
Signer(s): Example Signer
Reason(s): Approved
Location(s): Example City
ByteRange entries: 1 | /Sig markers: 1Shows how many signature markers and ByteRange entries the file has and any /Name, /Reason and /Location text; an unsigned PDF shows No digital signatures found in this PDF.
FAQ
Does it verify that a signature is valid?
No. It only searches the file for /Sig and /ByteRange markers and literal /Name, /Reason and /Location strings; it does not check the certificate, the signer's identity or whether the document changed after signing. Use Adobe Acrobat Reader or pdfsig to validate.
Can the result be wrong?
Yes. An empty signature field also contains /Sig, so an unsigned form can show markers, and one signature usually produces several /Sig matches; the ByteRange count is the closer estimate. A signature image pasted onto an invoice is not a digital signature and is not detected.
Is the PDF uploaded?
No. The file is read in your browser and never leaves it. The whole file is loaded into memory, so very large PDFs can be slow.