Password protect a PDF
Choose a PDF, type a password and download the protected copy. It asks for that password in any PDF reader: Acrobat, Preview, Chrome, a phone.
How it works
- Add your PDFDrag in or select the PDF file you want to work with.
- Type a passwordThe field shows what you type, so choose one you will remember. If the file already has a password, type that one first.
- Download the protected copyPress Protect PDF, then download. The copy asks for the password in any PDF reader; your original stays as it was.
Save and continue on the desktop
Download or copy your result here first. Open the free desktop to save to Files or use more features.
- Merge, split, sign and compress PDFs
- Save to Files when you continue on the desktop
- Every tool in one place, no new tabs
After you download, continue on the desktop for Files or the full app.
What Protect PDF can do
What the password does
The copy is encrypted with AES-256, the strongest method in the PDF standard and the one Acrobat uses. Without the password its pages, text and pictures are unreadable bytes, not content hidden behind a prompt. Every current PDF reader asks for it: Adobe Acrobat, Apple Preview, Chrome, Edge, Firefox and the viewers on phones.
A password you will remember
A forgotten password cannot be recovered or reset by anyone; that is what makes it a lock. The field shows what you type, so a typo does not lock you out; hide it if someone is looking. Length beats symbols: three or four unrelated words are harder to guess than a short word with a digit. Your original file stays as it was.
A PDF that already has one
If the file already asks for a password, type the current one and choose a new one: the copy opens only with the new password. A PDF that just blocks printing or copying is protected like any other, and the copy carries the password instead of those limits.
Related apps
Questions
How strong is the protection?
AES-256, with the key derived from your password the way revision 6 of the PDF security handler (ISO 32000-2) prescribes. Nobody reads the file without the password. A short or common password can still be guessed, so length matters more than anything else.
Is the download really free?
Yes. No account, no trial and no watermark of ours on the file: it is made in your browser, and you can save it as many times as you like.
Will it open on a phone or in Preview?
Yes. Current readers all open AES-256 PDFs once you type the password: Acrobat Reader, Apple Preview and Books, Chrome, Edge, Firefox, the Files app on Android. Only readers from before 2008 may not.
Can I stop people from printing or copying?
nopa does not set those flags. They are a request that each reader may honour or ignore, and many ignore it; anyone with the password can read the file anyway. If someone should not see the content, do not give them the password.
What if I forget the password?
It cannot be recovered. Keep the original file, or save the password in a password manager before you send the copy.
Are my file and password sent anywhere?
No. The encryption runs in your browser, on this device; nopa has no server that could receive either.