NEW · POWERED BY ELAI

Sign PDFs with cryptographic proof.

Hardware-grade signatures. Tamper-evident. No account needed. Anyone can verify your signed PDF — at any time, in any browser, with the link you'll get when you're done.

EXTRAORDINARY LINK ASSISTIVE INTELLIGENCE · THE LINK

1

Upload your PDF

Your file is processed in your browser. Nothing uploads anywhere until you click Sign.

Drop PDF here or click to choose
.pdf only · up to 50 MB
2

Choose your signing identity

No account. Identity is bound just for this signing event.

Anonymous FREE
Cryptographically signed. Identity = your ephemeral public key. Best for: personal use, proof of authorship at a moment in time.
Email-verified DAY PASS
Signature bound to a verified email address. Best for: contracts, NDAs, anything where a counterparty needs to know who signed.
Passkey-bound SOON
Hardware-bound via WebAuthn. Key never leaves your device's Secure Enclave / TPM. Best for: high-stakes legal docs.
CAC / EMV chip-card SOON
Federal credential or civilian chip-card. ISO 7816-4 INTERNAL AUTHENTICATE. Best for: federal, financial, regulated workflows.
3

Sign with ELAI

Drag the ELAI star to position it on page 1, and use the controls to resize or change its opacity. The signed manifest is embedded in the PDF and verifiable at 4pdfs.com/verify.html.

✓

Signed.

Your PDF has been ELAI-signed. Download it, and share the verify link with anyone who needs to confirm the signature.

Download signed PDF

How this works. Your PDF is hashed in your browser. The ELAI signing service signs the hash + your identity proof + a fresh nonce, then stamps the PDF and returns it. The original file content never leaves your computer in the clear. The verify page checks the signature without re-uploading the PDF.