Protect PDF
Lock a PDF with a password — AES-256, in your browser, with nothing uploaded.
- Runs in your browser
- Nothing is uploaded
- No account
- No watermark
Drop a PDF to lock it with a password
or · paste with ⌘/Ctrl + V
About
What Protect PDF does
Lock a PDF with a password, using AES-256 — the same encryption Acrobat writes. You can also restrict what a reader may do with it: printing, copying text and pictures, or making changes.
Everything happens on your own machine: the file is decoded, processed and re-encoded by your browser, and never leaves your device. There is no upload, no queue and no account.
Why this one
Why use Protect PDF here
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AES-256, as Acrobat writes it
The file is genuinely encrypted: without the password its contents cannot be read.
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Your password stays with you
The file is locked in your browser, so neither the PDF nor its password is sent anywhere.
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Restrict printing and copying
Add an owner password and choose what readers may do with the file.
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Free, with nothing to install
No limits, no sign-up and no watermark.
How it works
How to use Protect PDF
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Drop in a PDF, click to browse, or paste one from the clipboard.
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Type the password needed to open the file, and type it again to be sure.
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Optionally set an owner password and tick what the file withholds — printing, copying, changes.
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Download the protected PDF. The original on your disk is untouched.
Questions
Frequently asked
How do I password protect a PDF?
Drop the PDF here, type a password twice and press Protect. The locked copy downloads straight away; your original is untouched.
Can I password protect a PDF without Adobe Acrobat?
Yes. This writes the same AES-256 encryption Acrobat does, in your browser, for free. Any PDF reader then asks for the password before it opens the file.
How strong is the encryption?
AES-256 with revision 6, which is what Acrobat and every current reader use. The file's contents are genuinely encrypted, and the password is the only way in — there is no recovery if you forget it, by us or by anyone.
What is the owner password for?
It separates 'who may open this' from 'who may change what it allows'. Leave the open password empty and set only an owner password, and anyone can read the file while printing or copying stays withheld until the owner password is given.
Do the restrictions actually stop anyone?
Not reliably, and we would rather say so. Restrictions on a file that opens without a password are a request that readers honour by convention — ours does. Any tool that chooses not to can ignore them, and stripping them takes seconds. They stop the honest and nobody else. An open password is the part with real force behind it.
Is my password sent anywhere?
No. The file is encrypted in this page, on your machine. The password is never transmitted, never stored, and is gone when you close the tab.
Is Protect PDF free?
Yes, with no limits, no account and no watermark.
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