PDF signature checker
Inspect PDF signature dictionaries and list SubFilter and ByteRange values. This is a structural check only; certificate trust is not verified.
// About this tool
Find out whether a PDF contains signature entries and how they are declared. Useful for debugging signed documents, but it does not validate certificates or document integrity.
// How to use it
- Choose a PDF file from your device.
- Review the detected signature count.
- Check each SubFilter and ByteRange entry.
// Frequently asked questions
Does this verify that a signature is valid?
No. It only inspects signature structures and does not validate certificate chains or trust.
Is my PDF uploaded?
No. The file is read locally in your browser.