Signing a PDF used to mean print, sign, scan, send. Then it meant paste a JPG of your signature. Both work, but neither is a real signature.
A digital signature carries a certificate, a timestamp, and a content hash. Tampering breaks it instantly. Most jurisdictions treat it as legally binding.
Why digital beats scanned
A scanned signature can be lifted off any document you've ever sent and pasted anywhere. There's no way to verify it's yours, on this specific document, at this specific time.
Digital signatures lock the content. Any change to the document after signing invalidates the signature. That's the whole point.
Sign with Flint
Open the PDF in Flint's signing tool. Draw, type, or upload your signature. Place it on the signature line. The tool generates a cryptographic signature attached to the document hash.
The signature includes a timestamp from a trusted timestamping authority. That answers the "when was this signed?" question definitively.
Send for countersigning
If the contract needs another party's signature, send the signed PDF. They open it, see your verified signature, and add theirs. Each signature is independent and verifiable.
For multi-party agreements with set signing orders, look at structured e-signature workflows. Flint handles two-party signings natively.
Verify on receipt
When a signed PDF comes back, open the signature panel in any reader. "Signed and all signatures are valid" with the signer's name means it's intact.
If the panel shows "Signature is invalid" or "Document has been modified", something changed after signing. Flag it before acting on the document.
FAQ
Is a digital signature legally binding?
In most jurisdictions, yes. EU eIDAS, US ESIGN, UK Electronic Communications Act all recognise digital signatures. Specific requirements vary; for high-stakes contracts, consult a lawyer in your jurisdiction.
Do I need a certificate from a CA?
For the strongest signatures (qualified electronic signatures in EU), yes. For most business uses, a self-signed or service-issued certificate is acceptable.
Can I sign on mobile?
Yes. Flint's signing tool works on mobile browsers. Draw your signature with your finger or stylus.
Will the recipient know what software I used?
The signature panel shows the signing tool and certificate. Recipients can verify the chain back to a trusted authority if applicable.
Does signing prevent editing?
Editing invalidates the signature. The file can still be opened and read, but the "signed and valid" status is lost.
A real signature on a PDF is faster than a scan and stronger evidence. Sign with Flint once and you'll never paste a JPG again.