Digital Signature
Sign a PDF with your own certificate file (.pfx, .p12 or .pem), in your browser. A PDF reader can then tell if the file was changed; whether it trusts the signer depends on your certificate.
About This Tool
Digital Signature signs a PDF with a certificate and private key that you supply. A PDF reader can then show whose certificate signed the file and whether the file has been changed since. A drawn signature cannot do that: it is a picture on the page. What the signature is worth in law depends on your certificate and on the rules that apply to you, not on this tool.
Choose a .pfx or .p12 file, or a .pem file that holds both the certificate and its private key, and type its password if it has one. Only RSA keys work. You can add a reason, a location and contact details, and tick "Add visible signature" to put a line of text, a PNG or JPEG picture, or both on the first page, the last page or every page; otherwise the signature is invisible. The text may be in any language: text the built-in font cannot write, such as Arabic, is put in as a picture of the text. The signing time comes from your device's clock: no time-stamping service is used. A reader shows the signer as trusted only if it already trusts your certificate, so a certificate you made yourself is reported as unknown until the recipient adds it.
The PDF, the certificate and its password stay in your browser; nothing is uploaded, and nothing is asked of any other site. The certificates in your file go into the signature, your issuer's among them when the file holds it, so that a reader can follow the chain. A certificate the file does not hold is not fetched for it.
How to Use
Upload PDF
Upload the PDF document you want to digitally sign.
Load Certificate
Choose your certificate file (.pfx, .p12 or .pem). If it has a password, type it and click "Unlock"; a file without one loads at once.
Configure Signature
Fill in "Reason", "Location" and "Contact Info" if you want them recorded. Tick "Add visible signature" to place text or a picture, and choose the page; position and size are in points, and the position is measured from the top-left corner of the page.
Sign and Download
Click "Sign PDF", then download the signed file.
Use Cases
Legal Documents
Sign a contract or an agreement with your own certificate. Whether the signature is legally binding depends on the certificate and on the law that applies.
Business Approvals
Digitally sign invoices, purchase orders, and approval documents for audit trails.
Document Integrity
Ensure documents have not been tampered with after signing.
Frequently Asked Questions
What certificate formats are supported?
.pfx and .p12 files, with or without a password, and .pem files that hold both the certificate and its private key. The key must be RSA: a certificate with another kind of key is refused, and the page says why. Certificates from a certificate authority work, as do ones you made yourself.
Is the signature legally valid?
That depends on your certificate and on the law that applies to you; this tool cannot promise it. It makes a standard certificate-based PDF signature, timed by your device's clock, with no trusted timestamp and no revocation information. With a self-signed certificate a reader can confirm that the file is unchanged, but not who signed it. Where the law asks for a qualified or accredited signature, use the service of an accredited provider.
Can I add a visible signature?
Yes. Tick "Add visible signature", set its position and size, choose the first page, the last page or all pages, and type a text or choose a PNG or JPEG picture, or both. If you leave the text empty the tool writes "Digitally signed by", the name in the certificate and today's date, in the language of the page. Text in a script the built-in font lacks, Arabic for one, is drawn as a picture, so it cannot be selected or searched in the signed file.