Sign PDF

How it works

Choose a PDF, your certificate file (.p12 or .pfx), and its password. Before signing, we show who the certificate belongs to and how long it is valid. The signature can be invisible or visible: a box with text, an image (for example, your scanned handwritten signature, or a stamp), or a drawing made on screen, placed by dragging it onto the page.

The certificate and password never leave your browser, are not sent to any server, and are not saved: the page discards them when done, so you must select them each time. The content of the PDF is not modified; the signature is appended to the end of the file. If the PDF was already signed, your signature is added after existing ones.

What it is not: it is not a qualified signature, does not carry a timestamp, and does not query any online service, so it works offline. Adobe and other readers will only consider it valid if they trust the certificate issuer. Any subsequent change to the PDF, including with the other tools on this site, invalidates the signature: always sign last. Password-protected PDFs and certified PDFs that prohibit changes cannot be signed.

What is not preserved, and limits

• An advanced electronic signature (PAdES-B-B) created on your device with your certificate. It is not a qualified electronic signature and does not carry a timestamp: date and time are from your device.
• We have not yet tested it with Adobe Acrobat or Adobe Reader.
• PDF readers show the signature as untrusted unless they recognize the certificate issuer as trusted; with a self-signed certificate, it will always appear as untrusted.
• Any subsequent change invalidates the signature, including with other tools on this website: always sign last.
• Password-protected PDFs and certified PDFs that prohibit changes cannot be signed.
• This website does not provide legal advice: if you need a signature with specific legal validity, consult the requirements of your procedure.
• Very large files (over roughly 100-150 MB total, or with thousands of pages) may fail, especially on mobile devices, because everything runs in your device's memory.