Digital Signature (X.509)
Apply legally-binding X.509 digital signatures using PFX, P12, or PEM certificates. 100% private, local cryptographic signing.
Upload PDF to Sign
About This Tool
Go beyond simple "e-signatures." Our Digital Signature tool allows you to apply standardized X.509 cryptographic signatures that provide non-repudiation and document integrity. Using PFX, P12, or PEM certificates, you can seal your documents with the same level of security used by banks and government agencies.
This tool creates a cryptographic hash of your PDF. If even a single comma is changed after signing, the signature will show as invalid, protecting you against fraud. You can choose to add a Visible Signature (with custom text, reason, and location) or an Invisible Signature for backend verification.
Maximum Security Privacy: Signing requires your private key and password. Our tool performs the RSA/ECDSA cryptography locally in your browser. Your certificate file and password are never transmitted over the internet.
How to Use
Upload PDF
Select the document that requires a formal digital signature.
Load Certificate
Upload your .pfx or .p12 file and enter the password (processed locally).
Configure Signature
Place the signature box, add a reason (e.g., "I approve this document"), and set the location.
Cryptographic Sign
The tool signs the file. Download your legally-protected PDF.
Use Cases
Legal Contracts
Sign business agreements that require verifiable cryptographic proof of identity.
Corporate Invoicing
Issue digital invoices that comply with international e-invoicing standards.
Certified Documents
Send official transcripts or certificates that users can verify for authenticity.
Frequently Asked Questions
What is the difference between this and a "drawn" signature?
A drawn signature is just an image. A digital signature is a mathematical proof that binds your identity to the document and detects any later tampering.
Can I use a self-signed certificate?
Yes, you can. While professional CA-issued certificates are preferred for high-stakes legal work, self-signed certificates work perfectly for internal company workflows.
Is my certificate password safe?
Yes. The password is used by the local WebAssembly library to decrypt the key in your RAM. It is never sent to our servers.