Digital Signature

About this tool

Digital Signature for PDF — Sign with Your .p12 Certificate (PAdES)

Sign a PDF cryptographically with your own .p12 or .pfx certificate and an RFC 3161 timestamp. The document, the certificate and its password never leave your browser.

A Real Signature, Not a Picture

Toolula writes a PAdES (ETSI.CAdES.detached) signature into the PDF: any later change to the file breaks it, and Acrobat or any PAdES validator shows who signed and when.

Your Certificate Stays on Your Device

The .p12 / .pfx is opened in the browser tab and its private key is held as a non-exportable Web Crypto key. Only a 32-byte fingerprint goes to the time-stamp authority.

Visible Stamp, Existing Signatures Kept

Place a signature stamp anywhere, add your handwriting if you like, and sign documents that already carry signatures — the new one is appended as an incremental update, so earlier ones stay valid.

Frequently asked questions

Is this signature legally valid under eIDAS?

With a certificate from a recognised CA that identifies you, the result is an advanced electronic signature (AdES) in the PAdES format. A qualified electronic signature (QES) additionally requires a qualified certificate on a qualified signature device such as a smart card or remote HSM, which a .p12 file is not.

Why does Acrobat say the signer's identity is unknown?

Acrobat shows a green check only when the certificate chains to the Adobe Approved Trust List or the EU Trusted Lists. Self-signed and test certificates still prove the document is unchanged, but not who signed it.

Is my certificate or password uploaded?

No. The PDF and the certificate are read inside your browser tab. With the timestamp switched on, only the SHA-256 hash of the signature value is sent to a public RFC 3161 time-stamp authority.

Is it really free?

Yes. Every Toolula PDF tool is free with no account, no trial and no daily limit — there is no server cost to pass on because your own device does the work.