How does PDF SignCheck verify a PDF digital signature?

PDF SignCheck cryptographically validates the digital signatures embedded in PDF documents. It checks that the document has not been tampered with after signing, verifies the signer's certificate chain against trusted root Certificate Authorities (CAs), and outputs a stamped PDF with a "Verified ✓" badge — similar to clicking "Trust this certificate" in Adobe Acrobat.

Is my PDF document stored or saved during digital signature verification?

No. Your file is processed entirely in memory on the server. It is never written to disk, never stored in any database, and is discarded immediately after the verified PDF is returned to your browser. We take privacy seriously — your documents remain yours.

What types of PDF digital signatures and certificates are supported?

PDF SignCheck supports PDFs that contain PKCS#7 / CMS digital signatures — the standard used by government portals, official certificate authorities, and digital signing platforms. This includes documents from DigiLocker, e-District, MCA, UIDAI, and similar government services worldwide.

Why does Adobe Acrobat Reader display a PDF signature as "Not Verified"?

Adobe Acrobat only trusts certificates from its own Adobe Approved Trust List (AATL). Many government and institutional signers are not on that list. Our tool auto-trusts the signer's certificate after cryptographic verification — exactly what Adobe asks you to do manually when you click "Trust this certificate." The downloaded verified PDF includes a visual stamp so it's clear the signature has been validated.

Is the online PDF signature verification process cryptographically secure?

Yes. We perform full PKCS#7 signature verification: we extract the signed hash from the signature, independently compute the hash of the document's byte ranges, and compare them. We also validate the certificate chain up to a trusted root CA from the Mozilla CA trust store. This is the same process that Adobe Acrobat and other professional PDF tools use.

Are there daily or rate limits for PDF cryptographic verification?

To prevent abuse, we rate-limit to 10 requests per minute per IP address. The maximum file size is 50 MB. These limits are sufficient for normal usage. If you need higher throughput for enterprise use, please contact us.

Which Indian government certificates and portals are supported?

PDF SignCheck fully supports digital signature verification for official Indian government certificates. This includes UIDAI Aadhaar Cards, state e-District certificates (such as Caste, Income, Domicile, and Birth/Death certificates), DigiLocker-issued PDF documents, NFSA Ration Cards, Income Tax / PAN documents, and any official PDF signed via CCA India (Controller of Certifying Authorities) root credentials.

How do I resolve the "Signature Not Verified" or "Signature Not Checked" warning on Aadhaar or Caste certificates?

Simply upload your signed PDF to PDF SignCheck. Our system extracts the digital signature, cryptographically validates the hash integrity against trusted root certificates, and generates a stamped PDF. When you download this verified document, the signature will show as valid, making it suitable for direct submission.

About Us

About PDF SignCheck

Free, privacy-first cryptographic verification for digitally signed PDF documents.

What is our mission?

PDF SignCheck was built to solve a simple but frustrating problem: digitally signed government documents showing “Signature Not Verified” in standard PDF viewers like Adobe Acrobat.

Millions of official documents — Aadhaar cards, DigiLocker certificates, income tax returns, caste certificates, driving licenses — are digitally signed by Indian government Certifying Authorities. Yet when opened in Adobe Acrobat, they display a confusing yellow question mark because Adobe's proprietary trust list doesn't include these CAs.

We built PDF SignCheck to make cryptographic signature verification accessible, instant, and free — no installations, no manual trust configuration, no technical knowledge required.

How does PDF SignCheck verify digital signatures?

PDF SignCheck performs full PKCS#7/CMS cryptographic signature verification:

Signature Extraction: We parse the PDF structure to locate and extract PKCS#7 signature blocks embedded in the document.
Hash Verification: We independently compute the hash (digest) of the document's byte ranges and compare it against the signed digest to detect any tampering.
Certificate Chain Validation: The signer's certificate chain is validated against 80+ trusted root Certificate Authorities from the Mozilla CA trust store.
Verified Stamp Output: Once validated, we stamp the PDF with a visual “Signature Valid ✓” badge that renders correctly on any device, browser, or PDF reader.

For a detailed technical walkthrough, read our complete guide on verifying PDF digital signatures.

How do we guarantee privacy and security?

We understand that digitally signed documents often contain sensitive personal information. Our privacy commitments:

🔒 Zero Storage PolicyFiles are processed entirely in-memory. Nothing is ever written to disk, stored in a database, or retained after verification completes.

🛡️ No Data CollectionWe do not read, log, or analyse the contents of your PDF documents. Only the cryptographic signature metadata is processed for verification.

⚡ Immediate DiscardOnce the verified PDF is returned to your browser, all in-memory data is immediately garbage-collected. There is no backup, no cache, no retention period.

Read our full Privacy Policy and Terms of Service for complete details.

What is the technical stack behind PDF SignCheck?

PDF SignCheck is built with modern, well-tested open-source technologies:

Cryptographic Engine: Built on node-forge for PKCS#7 parsing, hash computation, and certificate chain validation.
PDF Processing: Uses pdf-lib for PDF incremental saving and visual stamp embedding.
Certificate Trust Store: Validates against the Mozilla CA trust store — an open, community-maintained list of 80+ globally trusted root CAs.
Application Framework: Next.js with server-side processing for secure, fast verification.

Who founded PDF SignCheck?

PDF SignCheck was created by Minhaj, a developer who experienced the government document verification problem firsthand. After spending hours trying to manually trust Indian government CA certificates in Adobe Acrobat — only to realize the fix was computer-specific and didn't transfer — he built PDF SignCheck to automate the entire process.

The tool has since grown to support verification of documents from DigiLocker, UIDAI, Income Tax, e-District portals, and more. It serves users across India and internationally who need to verify and share government-issued PDFs.

How can you contact us?

For questions, feedback, or enterprise enquiries, reach us at:

Email: hi@pdfsigncheck.com
Feature Requests: Submit and vote on features
Advertising: Advertise on PDF SignCheck