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HomeCompress
Convert
JPGPDF to ImageConvert PDF pages to JPG/PNGWPDF to DOCXConvert PDF to Word documentsWWord to PDFConvert Word files to PDF
Edit PDF
Merge PDFCombine multiple PDFs into oneOrganize PagesRearrange PDF page orderEdit PDFAdd text, images to PDFRotate PagesRotate pages in PDF files
PDF Security
Add WatermarkBrand your PDFs with watermarksEncrypt PDFLock PDF with a passwordSign PDFAdd digital signature to PDF
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HomeAll ToolsSecure PDFDigital Sign PDF

Digital Sign PDF

Apply a digital certificate

Select a PDF file

Drag and drop files here, or click to browse

Ready to process

Upload a file to get started

  • Files never leave your device
  • Processed entirely in your browser
  • GDPR-conscious processing

About This Tool

Digital Signature allows you to add cryptographic X.509 digital signatures to PDF documents. Unlike simple drawn signatures, digital signatures provide legal validity and document integrity verification.

Upload your certificate file (PFX, P12, or PEM format), enter the password, and sign your PDF. You can add visible signatures with custom text, images, and positioning, or invisible signatures for document integrity only.

All signing happens locally in your browser. Your certificate and documents are never uploaded to any server.

How to Use

  1. 1

    Upload PDF

    Upload the PDF document you want to digitally sign.

  2. 2

    Load Certificate

    Upload your X.509 certificate file (.pfx, .p12, or .pem) and enter the password.

  3. 3

    Configure Signature

    Optionally add reason, location, and visible signature with custom text or image.

  4. 4

    Sign and Download

    Click Sign PDF to apply the digital signature and download the signed document.

Use Cases

Legal Documents

Sign contracts, agreements, and legal documents with legally binding digital signatures.

Business Approvals

Digitally sign invoices, purchase orders, and approval documents for audit trails.

Document Integrity

Ensure documents have not been tampered with after signing.

Frequently Asked Questions

What certificate formats are supported?

PFX (.pfx), PKCS#12 (.p12), and PEM (.pem) certificate formats are supported.

Is the signature legally valid?

Yes, X.509 digital signatures are legally recognized in most jurisdictions when using a valid certificate.

Can I add a visible signature?

Yes, you can add a visible signature with custom text, image, position, and styling.

You May Also Like

Validate Signature

Verify digital signatures

Secure PDF

Protect PDF

Encrypt with password protection

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Sign PDF

Draw or type your signature

Edit & Annotate

References

  • Digital signature – WikipediaHow digital signatures work cryptographically to authenticate documents.
  • Public key infrastructure – WikipediaPKI: the certificate chain behind digital signatures.
  • Validate SignatureVerify the integrity of a digitally signed PDF.

Every tool you need to work with PDFs — fast, private, self-hosted.

Product
  • All tools
  • Pricing
Categories
  • Organize & Manage
  • Edit & Annotate
  • Convert to PDF
  • Convert from PDF
  • Optimize & Repair
  • Secure PDF
Company
  • About
  • Contact
  • Blog
  • Help Center
Legal
  • Terms
  • Privacy
  • Security
  • Refund Policy
© 2026 pdfsimple. All rights reserved.