Digitally Sign a PDF
Add a real cryptographic signature that proves who signed it and that it hasn't been changed since — not just a picture of a signature.
How it works
1. Upload your PDF. 2. Create a free signature on the spot, or upload a certificate (.pfx/.p12) you already own. 3. Download — the PDF now carries a real digital signature any PDF reader can check.
How is this different from Fill & Sign?
Fill & Sign stamps a picture of your signature onto the page — it looks right, but there's nothing stopping someone from editing the file afterward without you knowing. This tool embeds a real cryptographic signature: any PDF reader can verify it and will flag the file if even one byte changes after signing.
What's the difference between the two signing options?
"Create a free signature" generates a certificate on the spot, tied to the name and email you enter — it proves the file wasn't altered after signing, but since no certificate authority vouches for your identity, PDF readers show it as unverified until someone chooses to trust it. "Use my certificate" lets you sign with a .pfx/.p12 file you already own (for example an Indian DSC used for tax, GST, or tender filings) — since a recognized authority issued it, readers that trust that authority show the signature as verified automatically.
Is a self-signed signature legally valid?
That depends on your country and use case — cryptographically it proves integrity (the file hasn't changed) and who signed it, but it doesn't carry the same automatic legal weight as a signature from a licensed certificate authority. Check your specific requirements before relying on it for contracts or filings.
Is my certificate password or private key ever sent anywhere?
No — everything happens in your browser. Your certificate, its password, and the private key never leave your device.
Which laws actually recognize signatures like these?
Most countries have some law covering electronically signed documents — the US ESIGN Act and UETA, the EU's eIDAS regulation, India's IT Act 2000, and similar rules elsewhere. But these laws almost always draw a line between a signature backed by a certificate a recognized authority issued and one you generated yourself. A DSC signed with "Use my certificate" is the kind these laws were built around. A signature from "Create a free signature" cryptographically proves the file wasn't tampered with, but it doesn't get the same automatic recognition — treat it like any other self-signed certificate.
Can I send this to someone else to sign, or track multiple signers?
No — this tool signs a PDF that's already on your device, by you, right now. It doesn't email the file to anyone, collect signatures from other people, or give you a dashboard to track who's signed what. If you need to route a document to several signers and follow its status, you'll need a dedicated e-signature workflow service instead.
How does someone else verify the signature once I send them the file?
They open it in a PDF reader that checks digital signatures — Adobe Acrobat or Reader does this automatically and shows a signature panel with a checkmark or warning icon. Clicking it shows whether the document has changed since signing and who the certificate says signed it. If you signed with "Use my certificate" and the reader already trusts that CA, it shows as verified with no extra steps; a self-signed certificate shows as valid-but-unverified until the recipient chooses to trust it.
Related reading