Digitally Sign PDF
Cryptographically sign a PDF with your certificate (.p12/.pfx) — tamper-evident PAdES-B-B. Signing happens in your browser; your private key is never uploaded.
Drop a PDF here or click to choose
Your PDF and private key stay in your browser.
No certificate? Generate a self-signed one for testing:
⚠️ Self-signed certificates are cryptographically valid but appear as "untrusted" in PDF readers. For trusted or legal signatures, use a certificate from a Certificate Authority.
Add a certificate-based digital signature to any PDF directly in your browser. Load your own .p12 or .pfx certificate to cryptographically e-sign contracts, invoices, or official documents, producing a tamper-evident PAdES-B-B signature that proves authenticity and integrity. Everything runs locally, so your private key, password, and file never leave your device.
How to Digitally Sign PDF
- Add the PDF you want to sign and load your .p12 or .pfx certificate file.
- Enter your certificate password so the key can be unlocked locally in your browser.
- Sign the document and download the cryptographically signed, tamper-evident PDF.
Frequently asked questions
Is my private key or password ever uploaded?
No. The entire signing process runs in your browser, so your certificate, private key, password, and PDF stay on your device and are never sent to any server.
What signature standard does this produce?
It creates a PAdES-B-B digital signature, a tamper-evident standard widely recognised by PDF readers and authorities for verifying a document's authenticity and integrity.
Which certificate formats are supported?
You can sign with a PKCS#12 certificate in either .p12 or .pfx format, the same files commonly issued by certificate authorities and government e-signature schemes.
Is it safe to sign confidential documents here?
Yes. Because signing happens entirely offline in your browser, sensitive contracts and legal files are never transmitted, making it safe for confidential and private documents.
Is there a file size limit or cost?
The tool is completely free with no sign-up, and there is no fixed size cap. Processing depends on your device's memory, so very large PDFs may sign more slowly.
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