PDF signature checker

THE PRACTICAL GUIDE · NORMANDIN SYSTEMS

Get more from PDF signature checker

PDF Signature Checker inspects embedded signature data in the PDF you select and displays the available signature and certificate details. It does not rewrite, encrypt, or sign the document. A cryptographic signature is different from a picture of a handwritten signature: only the former provides embedded signing data for this kind of inspection. Review each reported signature individually and distinguish document-integrity information from trust in the signer. Certificate chains, revocation, timestamps, and permitted later changes can require a broader validation process. Keep the exact original file for any follow-up review, because printing, merging, or otherwise rewriting a PDF creates a different artifact and can change what a signature checker is able to assess.

Guide updated October 13, 2026

How to use this tool

1. Drag the original PDF onto the upload area or use its file picker to select it. Inspection begins after the file is selected.
2. Confirm the displayed filename and size so you know which document is being inspected.
3. Read the available details for every detected signature, and distinguish a no-result or error state from a positive validation result.
4. Compare relevant findings with the validation details in an appropriate PDF reader if signer trust or later document changes matter to your workflow.

SEE IT IN PRACTICE

A worked example

A PDF containing a cryptographic digital signature

A report for the embedded signature and supported validation details

The checker is examining signature data stored in the document; a visible signature image alone does not create such data.

What a signature check can establish

An embedded cryptographic signature connects signed document bytes with signing information. A check can reveal whether supported signature data is present and whether the relevant cryptographic relationship is consistent. That is different from seeing a handwritten signature image on a page. It is also different from deciding whether the certificate belongs to the expected person, whether a trust chain is acceptable, or whether revocation information is available. Read the individual report fields and warnings rather than reducing the entire result to a single visual impression of a signed document.

Multiple signatures and later changes

A PDF can contain more than one signature and can be updated incrementally after an earlier signature. The interpretation depends on which revision was signed and what changes followed it. Review every reported signature and compare the outcome with a PDF reader appropriate to your organization's validation process. If the report says no signatures were found, it may still contain a visible signing mark that is simply not a cryptographic signature. Preserve the original byte-for-byte file when investigating authenticity; printing, merging, or rewriting it creates a different artifact for validation purposes.

When this tool is useful

• Inspect a digitally signed document
• Distinguish signature images from embedded signatures
• Investigate whether a signed PDF reports later changes

Tips for a better result

• Keep the byte-for-byte original PDF. A printed, scanned, or rewritten copy cannot substitute for the original embedded signature evidence.
• Read all reported signature details rather than relying on a visible signature mark or a single favorable field.
• If no usable signature report appears, inspect the file in another appropriate reader. A picture of a signature is not an embedded cryptographic signature.

Frequently asked questions