Digital Signature Validator
Verify the cryptographic integrity of digitally signed PDF files completely offline. Audit byte ranges, changes, and signer certificates.
Drag & drop signed PDF to validate
or click to choose files from your device (.pdf)
How Signature Validator Works
Audit and verify the cryptographic layout of your signed documents in 3 simple steps.
Select Signed File
Drag and drop your signed PDF document into the local sandbox workspace.
Verify Integrity
The client-side scanner analyzes internal signature block structures.
Examine Certificates
Review signer identifiers, validity ranges, algorithms, and change logs.
Why use our Signature Validator?
Verify legal compliance and verify that contracts have not been tampered with since they were signed.
Confirm Post-Signing Modifications
Analyze document byte ranges (`/ByteRange`) to see if any objects or layout elements were appended after signing.
Examine Public Key Details
Extract Common Name (CN), Organization (O), Email, and date ranges of validity directly from the public keys.
100% Client-Side Sandbox
Document data, signatures, and certificates are evaluated entirely in the browser memory offline.
Frequently Asked Questions
Common queries regarding local PDF cryptographic verification.
Q.What does VALID status mean?
It means the signature's mathematical envelope is cryptographically sound, matches the public key certificate, and no changes were made to the document since the signature was written.
Q.What is a ByteRange check?
It verifies the signed data bounds. If the final PDF file is larger than the signature byte range offsets, this indicates modifications were appended after the document was signed.
Q.Are my documents secure?
Yes. Verification is performed locally in your browser memory using public-key parsing scripts. No documents are uploaded to our servers.
Q.What should I do if a signature status is 'MODIFIED_AFTER_SIGNING'?
This status indicates that incremental updates or data bytes were appended to the file after the signature was created. You should treat the document as untrusted and contact the signer to obtain the original, unmodified copy.
🛠️ Discover Related Verification & Security Tools
For comprehensive signature auditing and compliance validation, check out our full range of client-side PDF utilities. Inspect credential details with the Signature Certificate Viewer, confirm real-time validation compliance via the PDF LTV Validator, verify security thresholds using the PDF Password Strength Checker, or examine operational rights with the PDF Permission Auditor.
How It Works
Our high-performance online utility runs entirely client-side, processing your files securely and instantly inside your web browser. For related functions, you can also use our PDF LTV and Certificate Viewer utilities.
Core Features
Designed for professional results, privacy, and maximum compatibility across all modern desktop and mobile browsers:
Frequently Asked Questions
Does this verify PDF digital signatures?
Yes. Validate signer certificates, reason values, byte ranges, and cryptographic integrity offline.