Drop files here, or click to browse
Max 100 MB · Single file
How to use
01
Upload the file
Drop your PDF, up to 100 MB, into the upload zone. The filename appears in a panel and page thumbnails render below, so you can confirm it's the right document.
02
Choose a password
Type the password in both fields — the confirmation catches typos before they lock you out. Use at least four characters; a long passphrase you haven't reused elsewhere is best for HR or payroll files.
03
Protect & download
Press Protect & download. The tool encrypts the file with AES-256 in your browser and saves a copy with a -protected suffix. Open it once and test the password before deleting the original.
Why Protect PDF
- Adds a real open password with AES-256 encryption — the same standard Acrobat uses.
- Everything runs in your browser: your PDF and password never leave your device.
- Anyone opening the file will be asked for the password first.
Common questions
Does this tool really encrypt the PDF in the browser?
Yes. It runs qpdf — the same battle-tested PDF security engine used on servers everywhere — compiled to WebAssembly, so full AES-256 key derivation and the PDF security handlers execute locally in your browser tab. The output is a genuinely encrypted document, identical to what a desktop tool produces, and neither the file nor the password ever leaves your machine.
How can I lock pdf with password at zero cost?
Right here — upload, set a password, download, no account and no watermark. If you prefer a desktop route, macOS Preview does it through File, Export, and the Encrypt checkbox, and LibreOffice Draw exports password-protected PDFs on Windows or Linux. All of these keep the file on your machine the whole time.
What settings matter most when protecting payroll or HR documents?
Use a passphrase you haven't reused elsewhere, and make it long — length beats complexity. This tool already makes the strong choices for you: it sets a real open password (the kind that actually encrypts the content, not just a permissions flag) and always uses AES-256.
Is it safe to encrypt pdf free through a random website?
Check the order of operations first. On most sites the file is uploaded before it's encrypted, so the most sensitive version travels bare to a stranger's server. This tool encrypts in your browser with WebAssembly — you can watch the network tab stay silent — which is the only order that makes sense for salary data, medical records, or contracts.
Does a permissions password stop someone from reading the file?
No. Permissions passwords only restrict printing, copying, and editing, and plenty of software ignores those flags. Only an open password, sometimes called a user password, encrypts the content so the document won't render without it.
Can recipients on old software open an AES-256 protected file?
Acrobat 9 and practically anything released in the last fifteen years handles AES-256 fine. If a recipient runs genuinely ancient software, AES-128 is the compatible fallback. Skip the legacy RC4 options entirely, they're breakable with cheap hardware.
What should I do with the unprotected original after emailing?
Remember the copies sitting in your Sent folder and your export directory. Delete the plain version or move it into an encrypted archive, because attackers go after mailboxes far more often than they attack AES.