Digital Signature
Sign a PDF with your own .p12, .pfx or .pem certificate in your browser. Adds an adbe.pkcs7.detached signature, optionally visible. No trusted timestamp.
Upload PDF to Sign
About This Tool
Digital Signature signs a PDF with a certificate and private key that you supply as a .p12 or .pfx file, or as a .pem file holding both. It adds a cryptographic signature of the adbe.pkcs7.detached type, using SHA-256 and the time from your device's clock. It is not a PAdES baseline signature and contains no trusted timestamp.
The key must be RSA; certificates with elliptic-curve keys are not supported. For a .p12 or .pfx file, or an encrypted .pem, you type its password and click Unlock, and the tool shows the subject, issuer and validity dates. An expired certificate triggers a warning but can still be used, and readers will then report a problem. If the certificate gives a web address for its issuer, your browser downloads the issuer certificates from there to complete the chain. That request goes to the certificate authority's server; the document and key stay on your device.
Optional fields add a Reason, Location and Contact Info. Tick Add visible signature to draw a box with text, a PNG or JPEG image, or both. X and Y are in points, with Y measured from the top of the page, so the defaults of 25 and 700 put the box near the bottom left of an A4 page. With no text or image, the box reads "Digitally signed by", the certificate name and the date. In this version the box always goes on the first page; the Last Page and All Pages choices are not applied.
Whether a recipient's reader treats the signature as trusted depends on the certificate. One from an authority on the reader's trust list can be accepted automatically; a self-signed one shows as unknown until the recipient trusts it. Sign the final version, because editing the file afterwards with a tool that rewrites it makes the signature fail. Read electronic vs digital signatures in PDFs before choosing, and use Sign PDF for a drawn or typed signature without a certificate.
How to Use
Add the PDF
Drop the finished document on Upload PDF to Sign, or click to browse.
Load your certificate
Choose a .pfx, .p12 or .pem file, enter its password and click Unlock. Check the subject, issuer and dates that appear.
Fill in the details
Optionally enter a Reason, Location and Contact Info. Tick Add visible signature to set the position, size, text, colour, text size or an image.
Sign and check
Click Sign PDF and download the _signed.pdf file. Open it in a PDF reader to see how the signature is reported before you send it.
Use Cases
Sign with an organisation certificate
Apply a certificate issued to you or your company to a final report, so recipients can see who signed and whether it changed afterwards.
Try out a signing workflow
Sign with a test certificate to see how your recipients' readers display signatures before you sign real documents.
Record an approval reason
Store a reason such as "Approved for release" inside the signature itself, alongside the signer details.
Frequently Asked Questions
Which certificate files can I use?
A .pfx or .p12 file containing a certificate and its private key, or a .pem file that contains both the certificate and the private key, encrypted or not. The key must be RSA; elliptic-curve keys are not supported. A certificate on its own, without its key, cannot sign.
Is this a PAdES or qualified signature?
No. The signature uses the adbe.pkcs7.detached format with SHA-256. It is not a PAdES baseline signature, it has no trusted timestamp and no long-term validation data, and the tool cannot use signing cards or remote signing services, which qualified signatures normally need.
Where does the signing time come from?
From your device's clock. No timestamp authority is contacted, so the time is the signer's own statement and is wrong if the clock is wrong.
Why does the recipient see the signer as unknown?
Readers trust certificates that chain to an authority on their trust list. A self-signed or in-house certificate shows as unknown or not trusted until the recipient decides to trust it. That on its own does not mean the file was altered.
Can the visible signature go on the last page?
Not in this version. The page menu offers First Page, Last Page and All Pages, but the box is always placed on the first page. The cryptographic signature covers the whole document wherever the box appears.
Are my certificate and password uploaded?
No. The document, key and password are used in your browser tab. The only network request is the download of issuer certificates from an address listed in your certificate, when it has one.