Sign PDF, Add a Digital Signature
Digitally sign a PDF with your own certificate or a self-signed one, free, and 100% in your browser. Your file and certificate are never uploaded.
100% private, your PDF and certificate are processed in your browser and never uploaded.
How to digitally sign a PDF online
A digital signature does two things at once: it proves who signed a document and it proves the document hasn't changed since. Unlike a drawn or typed "signature" image, a real digital signature is cryptographic, if a single byte of the file changes afterwards, the signature breaks and any validator will flag it. This tool lets you add that kind of signature to a PDF without installing desktop software, and without your document ever leaving your browser.
Upload your PDF, choose how you want to sign, and click Sign PDF. You can either create a certificate instantly from your name, or use your own .p12 / .pfx certificate (such as an exported DSC). The signed file is ready to download in seconds.
Self-signed vs. a trusted certificate (DSC)
When you create a certificate here, it is self-signed: the signature is mathematically valid and tamper-evident, but no Certifying Authority vouches for your identity, so a verifier will show the certificate's root as "untrusted". That's perfectly fine for personal records, internal approvals, or demonstrating how signatures work.
For signatures that are legally and officially recognised, use a Digital Signature Certificate (DSC) issued by a licensed Certifying Authority (for example, under CCA India). Export it as a .pfx/.p12 file, choose "Use my .p12 / .pfx", and sign, the resulting signature chains to a trusted root.
Sign privately, nothing is uploaded
Signing a document often means handling sensitive content and a private key, so uploading either to a server is exactly what you don't want. This tool runs the entire signing process in your browser using the open-source @signpdf and node-forge libraries. Your PDF, your certificate file and its password are read into memory, used locally, and never transmitted.
Verify what you signed
Once you've signed, you can immediately check the result with our PDF signature validator, it will show the signature as intact and display the certificate details. Need to protect the signed file with a password too? Use Lock PDF.
Sign PDF, frequently asked questions
How do I digitally sign a PDF?+
Upload your PDF, choose to create a certificate from your name or upload your own .p12/.pfx certificate, then click Sign PDF. You'll get a digitally signed copy to download, signed entirely in your browser.
What's the difference between a self-signed and a CA certificate?+
A self-signed certificate is created on the spot from your name. The signature is valid and tamper-evident, but because no trusted authority vouches for the certificate, verifiers show the root as 'untrusted', fine for personal or internal use. A certificate issued by a licensed Certifying Authority (a DSC) chains to a trusted root and is recognised for legal and official use.
Can I sign with my DSC (Digital Signature Certificate)?+
Yes. Choose 'Use my .p12 / .pfx', select your certificate file, and enter its password. Many DSCs can be exported as a .pfx/.p12 file. The certificate and password are read in your browser and never uploaded.
Is my certificate safe?+
Yes. Signing runs entirely inside your browser. Your PDF, your certificate file and its password never leave your device, there is no upload.
Can I verify the signature afterwards?+
Absolutely, that's our main tool. After signing, open the PDF signature validator to confirm the signature is intact and inspect the certificate details.