Lock PDF
Add password protection to any PDF file. Set an owner password to restrict editing, printing, and copying — processed entirely in your browser.
Options
使い方
Upload the PDF you want to protect
Enter a password in the field
Download your password-protected PDF
よくある質問
What kind of protection does this add?
It sets an owner password that restricts editing, printing, and copying. Recipients will need the password to open the PDF.
Is my PDF uploaded to a server?
No. Everything runs in your browser using pdf-lib. Your PDF and password never leave your device.
Can I remove the password later?
Yes. Use the Unlock PDF tool on OneConvertly — enter the password and download an unlocked copy.
Can I lock a PDF on my phone?
Yes. OneConvertly works in any modern mobile browser including Safari on iPhone and Chrome on Android.
Is there a file size limit?
Files up to 200MB are supported. Processing speed depends on your device since encryption runs locally.
Is this tool free?
Yes, completely free. No signup, no watermarks, no daily limits.