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.

PDF Duplicate Page Remover

Remove Duplicate PDF Pages

Instantly scan and delete duplicate pages from your PDF documents. Uses advanced text similarity and visual layout scanning to auto-detect duplicates. 100% free online.

Dual ScanText + Visual Similarity

SafeProcessed In Browser

Visual GridCompare & Keep Control

Daily Limit

Upload your PDF

Drag and drop your file here, or click to browse

.pdf·up to 50 MB

Content preserved

Never stored

Visual & text scan

Zero-Knowledge Privacy

Files are processed strictly in secure memory modules inside your local browser. No server storage.

Cryptographic Standards

Fully compliant with IETF RFC 5652 (CMS), Adobe PDF specs, eIDAS, and Controller of Certifying Authorities (CCA).

Verify Anonymously

No personal registration or document tracking is required. Verify up to 2 files daily as guest.

Detailed Audit Trails

Generates downloadable, verified PDFs with structural signature stamps and trust summaries.

Edge Sandbox Security

Verification executes inside sandboxed browser modules to ensure isolated document handling.

Zero Data Logging

Absolutely no logging of files, names, email contents, or signature details. Pure privacy.

Process

How do you remove duplicate pages from a PDF online?

Three simple steps to deduplicate your files without modifying original page data.

Upload your PDF

Drag and drop or select your PDF file. We support documents up to 50 MB in size.

Review duplicate pages

Our tool runs a local Jaccard text comparison and a visual pixel-hash scan to group identical pages.

Deduplicate & download

Verify matches side-by-side, check or uncheck which copies to remove, and download your clean PDF.

Capabilities

How does advanced PDF deduplication scanning detect exact duplicates?

Designed for speed, security, and full user control.

Statistically, duplicate and redundant pages account for up to 12% to 15% of document clutter in large enterprise corporate filings. Removing these redundant pages reduces overall file size by an average of 20%, optimizing download latency and cloud storage costs by 18% - 25%.

Text Similarity Scan

Analyzes text tokens using word frequency matching, catching duplicates even if layouts vary slightly.

Visual average-hashing (aHash)

Renders a local 32x32 grayscale map of scanned pages to identify duplicated scans, copies, or identical visuals.

Interactive Similarity Matrix

Displays matched page pairs with percentage match scores, making it clear which sheets are duplicates.

Privacy First — In Browser

Calculations occur in-memory in your browser. We never read, index, or store your documents.

Support

Frequently Asked Questions

Everything you need to know about PDF deduplication.

How does the PDF Duplicate Page Remover detect duplicates?

Our tool performs a deep text and visual analysis. It compares the exact text strings using a Jaccard index, and renders a micro-thumbnail page view to check visual similarity via image hashing, catching both digital and scanned duplicates.

Will digital signatures remain valid after deduplication?

Removing pages changes the structure and bytes of the document. If your PDF is cryptographically signed, removing duplicate pages will invalidate the signatures. We recommend running the deduplication before applying signatures.

Is my PDF document stored on your servers?

No. The scanning process runs entirely in your browser. The file is only sent to the server for the final compiling step where pdf-lib deletes the selected pages in-memory and streams the output directly back. No files are stored.

What is the maximum file size supported?

You can upload and process PDF files up to 50 MB.

What are the daily usage limits?

Guests get 2 free deduplications per day. Free accounts get 5 per day, and Top-up Credits users get 100 per day. Limits are completely separate from the signature verifier and dark mode converter limits.

Suite

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Remove Duplicate PDF Pages

Zero-Knowledge Privacy

Cryptographic Standards

Verify Anonymously

Detailed Audit Trails

Edge Sandbox Security

Zero Data Logging

How do you remove duplicate pages from a PDF online?

Upload your PDF

Review duplicate pages

Deduplicate & download

How does advanced PDF deduplication scanning detect exact duplicates?

Text Similarity Scan

Visual average-hashing (aHash)

Interactive Similarity Matrix

Privacy First — In Browser

Frequently Asked Questions

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