PDF Signature Checker
Check PDF for digital signatures and certificate information. Inspect signature fields without uploading. Free, private, browser-based.
Local processingWhat is PDF Signature Checker?
A PDF digital signature is a cryptographic signature embedded in a PDF that authenticates the signer and ensures document integrity. Signature fields contain the signer's certificate, signing time, reason, and location.
How It Works
The tool parses the PDF structure looking for AcroForm signature fields (type /Sig) and digital signature dictionaries. It extracts available metadata: signer name, signing date, reason, location, and certificate info.
Common Use Cases
- Checking if a PDF is digitally signed
- Extracting signer information
- Verifying document authenticity before processing
Technical Details
Parses PDF byte structure to find /Annots with /FT /Sig, /Type /Sig, and ByteRange entries. Extracts /Name, /M (signing time), /Reason, /Location from the signature dictionary. Uses pdf-lib for PDF parsing. No cryptographic verification is performed.
How to Use
- Select or drop a PDF file
- Click Check Signatures
- View signature details if found
Privacy
All processing happens in your browser. Your data is never uploaded to any server.
FAQ
Can it verify signature validity?
The tool detects signature fields and extracts metadata (signer, date, reason, location). Full cryptographic verification requires the signer's certificate chain and is not performed.
Is the PDF uploaded?
No. The PDF is parsed entirely in your browser using a JavaScript PDF library. No file is transmitted to any server.