Digital Sign PDF — Add Digital Signature Certificate Online Free
Apply a cryptographic digital signature to your PDF using your PFX/P12 certificate. Tamper-evident, standards-compliant.
How to digitally sign a PDF
- 1Upload your PDF file
- 2Upload your PFX/P12 certificate and enter its password
- 3Click 'Sign'
- 4Download the signed PDF
Features
- Cryptographic PDF signing using PFX/P12 certificate
- Document is protected against changes after signing
- Signer information is displayed in PDF viewers
- Browser-based — certificate and file are not uploaded to a server
Use cases
- Sign contracts, invoices, or agreements with a digital certificate
- Protect a PDF document from unauthorized modifications
- Confirm authorship and integrity when sharing a document
FAQ
Is a digital signature legally binding?
Digital signatures with valid certificates are legally binding in most jurisdictions.
What certificate format is required?
PFX or P12 certificates are supported. These can be obtained from a Certificate Authority.
Can I sign multiple pages?
Yes. The digital signature applies to the entire document, not individual pages.