Protect PDF (Password)
Password protect a PDF with AES-256 encryption from qpdf, then decide under Terms whether whoever receives the file may print the document, copy text out of it, or edit it at all.
The document
Drop a PDF and its pages show here
Document
Drop PDFs here
One file or a batch — it is encrypted on this device, so the password never leaves it
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The queue
Pages
What the recipient can do
Encryption
Locking a file
- Drop the document onto the Document box. More than one is fine; they queue up and share whatever password you set.
- Type the password into Password to open. It is the one a recipient has to enter before the document opens at all, and the eye button shows it for a last read-through.
- To decide on printing, copying or editing, open Terms, tick or untick Print, Copy text and Edit, and give Password to change these terms a different value.
- Press Protect PDF. A bar shows the run with a Cancel beside it, and a batch names each file as it is locked.
- Click Download, or Download all (.zip) for a batch. Then put the password somewhere you will still find it next year.
About this tool
Putting a password on a PDF once meant owning Acrobat. Here it takes a file, a password, and one button. The lock is AES-256, applied by qpdf compiled to WebAssembly, which is the same encryption Acrobat writes. A file protected on this page therefore prompts for the password in Acrobat, in macOS Preview, in Chrome and Edge, and in whatever PDF reader is already on your phone.
Open Terms and you set what the recipient can do: Print, Copy text and Edit, with Edit off to start, plus a second password for changing those terms. Leave that second field blank and it falls back to the password that opens the file, which the page says right under it. Your choice of terms is remembered for next time; neither password ever is. The page shows the document before you lock it, and after the run it opens the locked copy once more to check it really refuses to open without the password. The qpdf engine is a 1.3 MB download the first time you use the page and stays cached afterwards. Queue several PDFs at once and they all take the same password, a file that already has one is skipped and named, and Download all (.zip) bundles the rest as protected-pdfs.zip.
A contract on its way out by email
Say you are sending signed-terms.pdf to a client and would rather it not circulate around their office. Load it, type a password into Password to open, then open Terms and untick Copy text; Edit is already off. Leave Print ticked, because the client will want a copy for the file. The panel now reads: Recipients can print, but not copy text or edit.
Press Protect PDF, then Download. What lands is signed-terms-protected.pdf. Opening that in Acrobat brings up a password box, and once past it the copy and edit commands sit greyed out. Send the password by text rather than in the same email as the attachment.
Good to know
- AES-256 with no back door means what it says. Forget the password and the document is shut for good, by me and by anyone else.
- The permission tickboxes are advisory. Acrobat, Preview and browser viewers respect them, but the owner password can be stripped by free software, including the Unlock PDF page on this site. Only the user password really keeps a document closed.
Frequently asked questions
What is the difference between the user password and the owner password?
Password to open is the user password, and it is the one most people mean. Password to change these terms is the owner password: whoever holds it can print, copy, edit and lift the restrictions no matter what you unticked. Adobe calls the pair the Document Open and Permissions passwords. Leave the second field empty here and it copies the first, so anyone who can open the file can also change its terms.
Can someone get around the printing and copying restrictions?
A determined person can, and it takes about ten seconds with free software. Restrictions are a courtesy layer that mainstream readers agree to honor, useful for discouraging a casual copy-paste. Real protection comes from the user password, because without it there is nothing to read in the first place.
I forgot the password on a file I protected here. Anything I can do?
Nothing, honestly. Genuine AES-256 has no recovery route and I did not build a master key into the page. If you still know the password and want it gone, the Unlock PDF tool strips it back off. Otherwise your only copy is whatever original you kept before protecting it.
What if the PDF already asks for a password when I open it?
The page notices as soon as the file lands, says so, and offers Unlock PDF instead of failing after the button. Remove the old password there, come back, and set the new one. A file carrying only owner restrictions opens without a prompt, and that one re-encrypts fine with your new terms.
How long does the password need to be?
Fifteen characters or more; length is what makes it hard to guess, and no symbols are needed, so a passphrase of four unrelated words clears the bar easily. AES-256 is only as good as what you type in front of it, so a reused login password or a birthday undoes the whole exercise.
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