What does signature validation actually check?

Validation checks three things: (1) that the cryptographic signature is mathematically correct, proving the signer held the private key; (2) that the document has not been modified since the signature was applied; and (3) that the signing certificate was valid at the time of signing (not expired or revoked). If all three checks pass, the signature is valid.

Can this verify signatures from any certificate authority?

The tool can verify the cryptographic integrity of any PKCS#7 signature regardless of the issuing certificate authority. It will show you the full certificate details including issuer name, so you can determine whether you trust that CA. For organizational or self-signed certificates, you can review the certificate chain to make your own trust decision.

What if the document was modified after signing?

The validation will clearly indicate that the signature is invalid due to document modification. This means someone changed the PDF content after the signature was applied, which breaks the cryptographic seal. The original signer's intent is no longer guaranteed for the modified version.

Is it safe to validate sensitive signed documents with this tool?

Yes. The validation runs entirely in your browser using WebAssembly. Your signed PDF is loaded into browser memory for analysis and never transmitted to any server. This is safer than uploading signed contracts or certified documents to online validation services.

Validate Signature

Verify the digital signatures in a PDF document directly in your browser. Check whether signatures are valid, whether the document has been tampered with since signing, and review certificate details including issuer, expiration date, and trust chain. This is essential for legal professionals receiving signed contracts, procurement teams validating vendor submissions, and compliance officers verifying certified documents. The validation runs entirely locally via WebAssembly, so the signed documents you are checking never leave your device.

Requires certificate server

Powerful Validate Signature Features

Instant Verification

Get clear pass/fail results for every digital signature in the document within seconds.

Certificate Details

Review signer identity, issuing authority, validity dates, and full certificate chain.

Local Validation

Signed documents are analyzed on your device. No uploads to external validation services.

How To Validate Signature Online for Free

Upload Signed PDF

Drop your digitally signed PDF into the tool. The document stays on your device for the entire validation.

Review Validation Results

See a clear pass/fail status for each signature, along with certificate details, signing time, and integrity check results.

Export Report

Download a summary of the validation results for your records or to share with colleagues.

Everything You Need in a Validate Signature

Integrity Verification

Confirms the document has not been modified since signing. Any tampering is immediately detected.

Certificate Analysis

View subject name, issuer, serial number, validity dates, and key usage for each signing certificate.

Trust Chain Review

Inspect the full certificate chain from signer to root CA to evaluate trustworthiness.

Timestamp Verification

Verify embedded timestamps to confirm exactly when the signature was applied.

Multi-Signature Support

Validate all signatures in the document, including counter-signatures and approval signatures.

Browser-Based Analysis

WebAssembly performs all cryptographic verification locally. No documents leave your device.

Frequently Asked Questions

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