Digital Signature
Sign PDFs with a certificate so any later change is detected.
- 1Upload
- 2Customize
- 3Process
- 4Download
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Digitally Sign PDF Online
A digital signature cryptographically binds your certificate to the exact contents of the PDF. PDF readers such as Adobe Acrobat show who signed it and warn if the file is modified afterwards. Paperly signs in your browser with SHA-256 and RSA; your certificate, private key and password are never uploaded.
This tool runs entirely in your browser. Your files are never uploaded.
How to digital Signature
- UploadSelect or drop your PDF into the Digital Signature tool.
- CustomizeAdjust the settings to get exactly the result you need.
- DownloadProcess the file and download the result instantly.
Frequently asked questions
What is the difference between Sign PDF and Digital Signature?
Sign PDF places an image of your handwritten signature. Digital Signature embeds a cryptographic signature from a certificate, which proves who signed and that the document has not been changed since.
Which certificate should I use?
For legally recognised signatures, use a certificate issued by a trusted certificate authority or your organisation, exported as a .p12 or .pfx file. A new self-signed certificate is fine for internal use; readers will show the signer as "unknown" until the recipient trusts it.
Is my private key uploaded?
No. The certificate file and its password are read only in your browser and never sent to any server.
Why does Adobe say the signature validity is unknown?
This means the certificate is not on the reader’s trusted list, which is normal for self-signed certificates. The document integrity check still works; recipients can choose to trust your certificate.