Protect PDF
Encrypt and lock PDFs with a password using client-side cryptography. Keys never leave your device.
PDF Vault password-protects a PDF using standard encryption applied in your browser, so neither the file nor the password is ever transmitted.
Encrypting a document through an online service has an obvious flaw: to encrypt the file, that service must first receive the unencrypted file, and usually the password too. You have protected the document against everyone except the party you just handed both halves to.
PDF Vault applies encryption on your own machine. The password is used locally to derive the key and is never sent anywhere. The output is a standard encrypted PDF that opens in Acrobat, Preview, and any modern reader that prompts for a password.
Nothing you do here is uploaded. The file is read into your browser's memory, processed by WebAssembly on your own machine, and written straight back to your downloads folder. You can confirm it yourself: open DevTools, switch to the Network tab, and run the tool — there is no request carrying your document, because there is no server endpoint to receive it.
How to password protect a PDF offline
- Load the PDF you want to encrypt.
- Enter the password you want to require, and confirm it.
- Export the protected file.
- Send the password to the recipient through a different channel than the document itself.
What you get
- Standard PDF encryption. Opens in Acrobat, Preview, and every mainstream reader with a password prompt.
- Password never leaves the device. Key derivation happens locally; there is nowhere for us to log it.
- Works offline. Encrypt a document on a plane, on a train, or on an air-gapped laptop.
- No account. Nothing links the encrypted file back to an identity on our side.
Frequently asked questions
What happens if I forget the password?
The document cannot be opened, and we cannot help — we never had the file or the password. Store it in a password manager before you send the file.
Is this strong enough for confidential material?
It uses the PDF standard's encryption, which is appropriate for controlling access to a document in transit. It is only as strong as the password you choose, so use a long random one from a password manager.
Can I remove the password later?
Yes, with the Unlock tool, as long as you know the current password.