Digitally sign a PDF with your certificate
Use your certificate file (.pfx or .p12) to add a real, verifiable digital signature, not just a picture of one. Your certificate and its password never leave your device.
- Real PKCS#7 signature, SHA-256
- Shows in Adobe Reader's signature panel
- Visible signature box or invisible
- Certificate never uploaded
Click on the page to place your text.
How to digitally sign a PDF with your certificate
- Step 1Add your PDFDrop the document to sign.
- Step 2Choose your certificatePick your .pfx or .p12 file and type its password.
- Step 3SignDownload the signed PDF. Any later change shows up in readers.
Questions
Is my certificate uploaded?
No. The certificate file, its password and the PDF are read inside your browser, and the signature is made there. Nothing is sent anywhere.
Will Adobe show a green tick?
Adobe shows the signature as valid and the document as unchanged. It shows the signer as trusted only when your certificate comes from an authority on its trust list (such as a licensed certifying authority), or when you trust the certificate yourself. Self-signed certificates show as "identity unknown".
Can I use my DSC USB token?
Not in a browser: a token keeps the key inside the device and needs its own software. This tool works with certificate files (.pfx or .p12) that include the private key.
Which certificates work?
RSA certificates in .pfx or .p12 files, including older Windows exports. ECC certificates are not supported yet. Expired certificates are refused, because the signature would show as invalid.
Can I sign a PDF that is already signed?
Not yet. Adding a second signature needs an incremental save, which this tool does not do, so it leaves already-signed PDFs unchanged rather than break their signatures.