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Certificate Signature

Sign PDF with X.509 certificate

How it works:

  1. 1Upload a PDF file
  2. 2Upload your digital certificate (.pfx/.p12)
  3. 3Click "Sign with Certificate"

About this tool

Sign a PDF with a digital X.509 certificate to gain a stronger guarantee of identity and authenticity than a drawn or typed signature can offer, which is exactly what legal documents, official forms, and binding contracts often demand. The tool accepts standard .pfx and .p12 certificate files and lets you record details like the reason for signing and your location. Because certificates supply cryptographic proof of who you are and confirm the document hasn't been altered, the resulting signature carries legal weight in many jurisdictions and acts as a tamper-evident seal that reveals any post-signing changes. Crucially, your certificate and private keys are processed entirely within the browser on your own machine and never get transmitted anywhere. The signed PDF retains its full quality and is available to save immediately once signing completes. Built for lawyers executing contracts, government employees certifying official records, or anyone whose PDFs require verified, cryptographically backed signatures.

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Frequently Asked Questions

It works with standard X.509 digital certificates in .pfx and .p12 formats. You can also add details like the reason for signing and your location, which get embedded alongside the cryptographic signature in the document.
A visual signature just shows a graphic, while a certificate provides cryptographic proof of identity and document integrity. It creates a tamper-evident seal that reveals if the file was altered after signing, making it legally binding in many jurisdictions.
Yes. The certificate signature embeds a tamper-evident seal into the PDF. If the document is changed after signing, the signature becomes invalid, alerting recipients that the file's integrity was compromised after you signed it.
Yes. All signing happens locally in your browser, so your certificate and private keys never leave your device or get uploaded to any server. This keeps your sensitive credentials protected while you apply a verified signature.
It suits anyone needing verified, legally robust signatures, such as legal professionals signing contracts, government workers handling official documents, or businesses approving forms where cryptographic proof of identity and document integrity is required.

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