Verify PDF Signature
Upload a signed PDF and instantly inspect all digital signature fields. Check signer name, signing time, reason, SubFilter type, and ByteRange integrity - all processed locally in your browser with no file upload.
The tool will scan the AcroForm signature fields in your PDF and report each field's signer name, signing time, reason, location, SubFilter type, and structural completeness (ByteRange + Contents).
What this tool checks
- Presence of AcroForm signature fields
- Signer name, reason, location, and signing time metadata
- ByteRange and Contents structure integrity
- Certification (DocMDP) signatures
- SubFilter type (adbe.pkcs7.detached, adbe.x509.rsa_sha1, etc.)
Note: Cryptographic chain validation (certificate trust, timestamp authority, revocation checks) requires a full PKI environment and is beyond what a browser-only tool can perform. This tool reports signature structure and metadata only.
Upload a PDF above to get started.
Why Use Our Verify PDF Signature Tool?
Deep Signature Inspection
The verify PDF signature tool reads every AcroForm signature field and extracts the signer name, signing time, reason, location, SubFilter type, and the structural integrity of ByteRange and Contents.
Clear Visual Results
Each signature field is displayed as a color-coded card - green for signed, yellow for unsigned, red for malformed - so you can immediately see the status of every signature in the document.
Instant In-Browser Analysis
Verify PDF signatures in seconds directly in your browser. No queue, no waiting - the structural analysis runs locally using pdf-lib and results are shown immediately.
Private & Secure - No Upload
Your PDF is never sent to any server during signature verification. All analysis runs locally in your browser, keeping confidential signed contracts and legal documents completely private.
Common Use Cases for Verify PDF Signature
Legal Document Review
Verify that a signed contract, affidavit, or court filing contains a digital signature field before relying on it in legal proceedings - check signer name and signing time without dedicated PDF software.
Business Contract Audit
Quickly confirm that all parties have signed a PDF agreement before processing it. The tool lists every signature field and flags any that are still unsigned or structurally incomplete.
Compliance & Audit Checks
Verify that regulated documents such as financial reports, HR forms, and compliance certificates carry the required digital signatures before archiving or submitting to authorities.
Certificate & Credential Verification
Check that a PDF certificate, diploma, or professional credential carries a digital signature - and inspect its SubFilter type and metadata to understand the signing standard used.
Developer & PDF Debugging
Developers building PDF signing workflows use the tool to inspect ByteRange coverage, SubFilter type, and Contents structure to debug why a signature fails third-party validation.
Multi-Party Signing Workflows
When a PDF requires multiple signers, use the tool to check which parties have completed their signature fields and which are still pending before routing the document to the next approver.
Understanding PDF Digital Signature Verification
What is a PDF Digital Signature?
A PDF digital signature is a cryptographic stamp embedded in the document that binds the signer's identity to the file content at the time of signing. When you verify a PDF signature you are checking that the document carries this cryptographic stamp and that its structural components - the ByteRange coverage and the Contents (signature blob) - are intact. PDF signatures are defined as AcroForm fields with type /Sig and are used in contracts, legal filings, certificates, and regulated documents to provide non-repudiation and tamper evidence.
How Our Verify PDF Signature Tool Works
- Upload your PDF: Drop or select the signed PDF. The file loads in your browser using pdf-lib - no server upload, no external processing.
- Signature extraction: The tool walks the AcroForm field tree, identifies every /Sig field, and reads the signature value dictionary (/V) for each - extracting the signer name (/Name), reason (/Reason), location (/Location), signing time (/M), SubFilter type, ByteRange, and Contents.
- Results display: Each signature field is shown as a color-coded card with its metadata and structural status. The summary banner reports the overall state - no signatures, all signed, or partially signed.
What Each Field Means
- ByteRange: Defines which byte ranges of the PDF are covered by the signature hash. A present ByteRange means the tool can identify what data the signature claims to protect.
- Contents: The PKCS#7 or CMS signature blob - the actual cryptographic value. Its presence means a signature was applied; its cryptographic validity requires PKI verification.
- SubFilter: Identifies the signature encoding:
adbe.pkcs7.detached(most common),ETSI.CAdES.detached(PAdES/EU eIDAS), or older formats. - DocMDP: A certification signature that locks the document against certain modification types after signing - common in approved forms and certified PDFs.
Privacy, Security & Limitations
All analysis runs in your browser session using the open-source pdf-lib library. Your PDF is never uploaded to any server. This tool reports signature structure and metadata only - cryptographic certificate chain validation (OCSP, CRL, timestamp trust) requires a full PKI environment. For legally binding verification, use Adobe Acrobat, a qualified trust service provider, or a PKI SDK. This tool is free with no signup, no account, and no usage limits.
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Frequently Asked Questions About Verify PDF Signature
The tool scans the AcroForm signature fields in your PDF and reports each field's status - including signer name, signing time, reason, location, SubFilter type (e.g. adbe.pkcs7.detached), and whether the critical ByteRange and Contents data are structurally intact.
No - and this is an important distinction. Full cryptographic validation (certificate trust path, timestamp authority, OCSP/CRL revocation checks) requires a PKI environment with network access and root CA trust stores. Browser-only tools cannot perform this level of validation. This tool reports signature structure and metadata.
Signed means the field has a signature value dict with ByteRange and Contents present. Unsigned means the field is defined in the form structure but no signature has been applied yet. Malformed means a signature dict exists but lacks the required ByteRange or Contents data needed for cryptographic verification.
A DocMDP (Document Modification Detection and Prevention) signature is a special certification applied by the document author that specifies what changes are allowed after signing. When detected, the tool flags it - it means the document has been certified, not just signed.
SubFilter identifies the cryptographic format. Common values are: adbe.pkcs7.detached (PKCS#7 detached, most common), adbe.pkcs7.sha1 (legacy), adbe.x509.rsa_sha1 (older X.509), and ETSI.CAdES.detached (PAdES/EU eIDAS standard).
No. All signature analysis runs entirely in your browser using pdf-lib. Your PDF never leaves your device and is never sent to any external server, keeping sensitive documents completely private.
The tool will report "No Signatures Found" if the PDF has no AcroForm signature fields. This means the document is either unsigned or uses a mechanism not based on standard PDF AcroForm fields.
Yes, completely free with no account, signup, or usage limits required.