Sending a contract, invoice, or personal document by email and want only the intended reader to open it? The free Lock PDF tool adds password protection to your PDF in seconds, with no account and no upload. The password is applied locally in your browser, so even we never see it.
This tool is designed for everyday document privacy: freelancers protecting client deliverables, landlords sending tenancy agreements, or anyone sharing records that should not be opened by strangers. Choose a strong password — a mix of letters, numbers, and symbols — and share it with the recipient through a separate channel, never in the same email as the file.
Lock PDF
Add password protection to a PDF file.
Drop your file(s) here or click to browse
Your files never leave this browser — everything is processed locally on your device.
Note: the password you type is used only inside your browser and is never uploaded.
How to lock a PDF with a password
- Drop your PDF into the box above.
- Type a strong password in the password field.
- Click “Lock PDF with password”.
- Download the protected file and share the password with the recipient separately.
FAQs
Will the locked file open in any PDF reader?
Yes. The tool applies standard PDF password security (128-bit RC4, the same method desktop tools use), so the locked file opens in Adobe Reader, Chrome, Edge, Firefox, Preview, and mobile readers — they will simply prompt for the password.
Can I recover the file if I forget the password?
No. There is no backdoor and no recovery option — keep your password somewhere safe before locking important files.
Is my password uploaded anywhere?
No. Everything happens in your browser; the password never leaves your device.